See pksunkara/pgx_ulid#27 and this time the design should probably not have to pick between multiple traits like JsonInOutFuncs, PgVarlenaInOutFuncs, and InOutFuncs: there should be one way to serialize/deserialize it.

• https://www.postgresql.org/docs/16/sql-createtype.html
• https://www.postgresql.org/docs/current/catalog-pg-type.html