Hello
According to Appendix D. SQL Conformance
https://www.postgresql.org/docs/current/unsupported-features-sql-standard.html
the feature T801 JSON data type is unsupported. However, PostgreSQL has data types JSON and JSONB. Here (http://peter.eisentraut.org/blog/2023/04/18/postgresql-and-sql-2023) it is also said that T801 is supported.
Perhaps there are some technical details that I am not aware of. However, I wanted to point this out.
Best regards
Erki Eessaar