I built https://github.com/k0nserv/plid with Pgrx and had a great time. I did have to scale back some of the magic (dropping derive PostgresType etc), but even so the support pgrx provides is excellent. I also talked to the maintainers a bit in discord and they were super helpful.

The one downside of custom extensions is that you aren’t, AFAIK, able to use them with many hosted Postgres installs, notably AWS RDS.