I'm attempting to optimize extraction of values obtained from a REST API which returns json values in an array.

Here's an minimal, complete, and verifiable example that reflects exactly what I'm doing.

```
USE tempdb;

DROP TABLE IF EXISTS dbo.json_test;

CREATE TABLE dbo.json_test
(
    json_test_id                int                 NOT NULL
        IDENTITY(1,1)
    , some_uniqueidentifier     uniqueidentifier    NULL
    , some_varchar              varchar(100)        NULL
    , the_json                  nvarchar(max)       NULL
);

INSERT INTO dbo.json_test (some_uniqueidentifier, some_varchar, the_json)
SELECT 
        some_uniqueidentifier       = NEWID()
      , some_varchar                = CONVERT(varchar(100), CRYPT_GEN_RANDOM(64), 1)
      , the_json = (
            SELECT st.* 
            FROM sys.tables st
                CROSS JOIN sys.tables st2
            WHERE st.object_id = t.object_id FOR JSON AUTO
            )
FROM sys.tables t;

;WITH src AS 
(
    SELECT jt.some_uniqueidentifier
        , jt.some_varchar
        , top_array.[key]
        , top_array.[value]
    FROM dbo.json_test jt
        CROSS APPLY OPENJSON(jt.the_json, N'lax $') top_array
),
src2 AS
(
    SELECT src.some_uniqueidentifier
        , src.some_varchar
        , src.[key]
        , src.[value]
        , inner_key = inner_array.[key]
        , inner_value = inner_array.[value]
    FROM src
        CROSS APPLY OPENJSON(src.[value], N'lax $') inner_array
)
SELECT src2.some_uniqueidentifier
    , src2.some_varchar
    , src2.[key]
    , [name]                                = MAX(CASE WHEN src2.[inner_key] = 'name'                               THEN src2.[inner_value] ELSE NULL END)
    , [object_id]                           = MAX(CASE WHEN src2.[inner_key] = 'object_id'                          THEN src2.[inner_value] ELSE NULL END)
    , [principal_id]                        = MAX(CASE WHEN src2.[inner_key] = 'principal_id'                       THEN src2.[inner_value] ELSE NULL END)
    , [schema_id]                           = MAX(CASE WHEN src2.[inner_key] = 'schema_id'                          THEN src2.[inner_value] ELSE NULL END)
    , [parent_object_id]                    = MAX(CASE WHEN src2.[inner_key] = 'parent_object_id'                   THEN src2.[inner_value] ELSE NULL END)
    , [type]                                = MAX(CASE WHEN src2.[inner_key] = 'type'                               THEN src2.[inner_value] ELSE NULL END)
    , [type_desc]                           = MAX(CASE WHEN src2.[inner_key] = 'type_desc'                          THEN src2.[inner_value] ELSE NULL END)
    , [create_date]                         = MAX(CASE WHEN src2.[inner_key] = 'create_date'                        THEN src2.[inner_value] ELSE NULL END)
    , [modify_date]                         = MAX(CASE WHEN src2.[inner_key] = 'modify_date'                        THEN src2.[inner_value] ELSE NULL END)
    , [is_ms_shipped]                       = MAX(CASE WHEN src2.[inner_key] = 'is_ms_shipped'                      THEN src2.[inner_value] ELSE NULL END)
    , [is_published]                        = MAX(CASE WHEN src2.[inner_key] = 'is_published'                       THEN src2.[inner_value] ELSE NULL END)
    , [is_schema_published]                 = MAX(CASE WHEN src2.[inner_key] = 'is_schema_published'                THEN src2.[inner_value] ELSE NULL END)
    , [lob_data_space_id]                   = MAX(CASE WHEN src2.[inner_key] = 'lob_data_space_id'                  THEN src2.[inner_value] ELSE NULL END)
    , [filestream_data_space_id]            = MAX(CASE WHEN src2.[inner_key] = 'filestream_data_space_id'           THEN src2.[inner_value] ELSE NULL END)
    , [max_column_id_used]                  = MAX(CASE WHEN src2.[inner_key] = 'max_column_id_used'                 THEN src2.[inner_value] ELSE NULL END)
    , [lock_on_bulk_load]                   = MAX(CASE WHEN src2.[inner_key] = 'lock_on_bulk_load'                  THEN src2.[inner_value] ELSE NULL END)
    , [uses_ansi_nulls]                     = MAX(CASE WHEN src2.[inner_key] = 'uses_ansi_nulls'                    THEN src2.[inner_value] ELSE NULL END)
    , [is_replicated]                       = MAX(CASE WHEN src2.[inner_key] = 'is_replicated'                      THEN src2.[inner_value] ELSE NULL END)
    , [has_replication_filter]              = MAX(CASE WHEN src2.[inner_key] = 'has_replication_filter'             THEN src2.[inner_value] ELSE NULL END)
    , [is_merge_published]                  = MAX(CASE WHEN src2.[inner_key] = 'is_merge_published'                 THEN src2.[inner_value] ELSE NULL END)
    , [is_sync_tran_subscribed]             = MAX(CASE WHEN src2.[inner_key] = 'is_sync_tran_subscribed'            THEN src2.[inner_value] ELSE NULL END)
    , [has_unchecked_assembly_data]         = MAX(CASE WHEN src2.[inner_key] = 'has_unchecked_assembly_data'        THEN src2.[inner_value] ELSE NULL END)
    , [text_in_row_limit]                   = MAX(CASE WHEN src2.[inner_key] = 'text_in_row_limit'                  THEN src2.[inner_value] ELSE NULL END)
    , [large_value_types_out_of_row]        = MAX(CASE WHEN src2.[inner_key] = 'large_value_types_out_of_row'       THEN src2.[inner_value] ELSE NULL END)
    , [is_tracked_by_cdc]                   = MAX(CASE WHEN src2.[inner_key] = 'is_tracked_by_cdc'                  THEN src2.[inner_value] ELSE NULL END)
    , [lock_escalation]                     = MAX(CASE WHEN src2.[inner_key] = 'lock_escalation'                    THEN src2.[inner_value] ELSE NULL END)
    , [lock_escalation_desc]                = MAX(CASE WHEN src2.[inner_key] = 'lock_escalation_desc'               THEN src2.[inner_value] ELSE NULL END)
    , [is_filetable]                        = MAX(CASE WHEN src2.[inner_key] = 'is_filetable'                       THEN src2.[inner_value] ELSE NULL END)
    , [is_memory_optimized]                 = MAX(CASE WHEN src2.[inner_key] = 'is_memory_optimized'                THEN src2.[inner_value] ELSE NULL END)
    , [durability]                          = MAX(CASE WHEN src2.[inner_key] = 'durability'                         THEN src2.[inner_value] ELSE NULL END)
    , [durability_desc]                     = MAX(CASE WHEN src2.[inner_key] = 'durability_desc'                    THEN src2.[inner_value] ELSE NULL END)
    , [temporal_type]                       = MAX(CASE WHEN src2.[inner_key] = 'temporal_type'                      THEN src2.[inner_value] ELSE NULL END)
    , [temporal_type_desc]                  = MAX(CASE WHEN src2.[inner_key] = 'temporal_type_desc'                 THEN src2.[inner_value] ELSE NULL END)
    , [history_table_id]                    = MAX(CASE WHEN src2.[inner_key] = 'history_table_id'                   THEN src2.[inner_value] ELSE NULL END)
    , [is_remote_data_archive_enabled]      = MAX(CASE WHEN src2.[inner_key] = 'is_remote_data_archive_enabled'     THEN src2.[inner_value] ELSE NULL END)
    , [is_external]                         = MAX(CASE WHEN src2.[inner_key] = 'is_external'                        THEN src2.[inner_value] ELSE NULL END)
    , [history_retention_period]            = MAX(CASE WHEN src2.[inner_key] = 'history_retention_period'           THEN src2.[inner_value] ELSE NULL END)
    , [history_retention_period_unit]       = MAX(CASE WHEN src2.[inner_key] = 'history_retention_period_unit'      THEN src2.[inner_value] ELSE NULL END)
    , [history_retention_period_unit_desc]  = MAX(CASE WHEN src2.[inner_key] = 'history_retention_period_unit_desc' THEN src2.[inner_value] ELSE NULL END)
    , [is_node]                             = MAX(CASE WHEN src2.[inner_key] = 'is_node'                            THEN src2.[inner_value] ELSE NULL END)
    , [is_edge]                             = MAX(CASE WHEN src2.[inner_key] = 'is_edge'                            THEN src2.[inner_value] ELSE NULL END)
FROM src2
GROUP BY src2.some_uniqueidentifier
    , src2.some_varchar
    , src2.[key]
ORDER BY src2.some_uniqueidentifier
    , src2.some_varchar
    , src2.[key];
```

The [query plan](https://www.brentozar.com/pastetheplan/?id=Skcotv1AO) uses a couple of nested loops joins regardless of how many rows are contained in the input table.  Presumably that's an artifact of using the `CROSS APPLY` operator.  For your fun, I've already set up a [DB Fiddle](https://dbfiddle.uk/?rdbms=sqlserver_2019&sample=adventureworks&fiddle=a548cf359ff55fa77a16677cc05050d6).

Is there a more efficient way of getting the data out of json format into a "real" set of columns?

I created the code above using my on-prem SQL Server 2019 instance, however the target will be Azure SQL Database, so all the latest-and-greatest options are available.