I get full type support by serializing and deserializing protobuf messages from a db column and not making this column JSONB means i can filter this column too, instead of having to flatten the searchable data to other columns.
You just have to be vigilant about correctly migrating existing data to the current shape if you ever make breaking changes to types.
For now i use sqlite to deal with transactions and only make backward compatible updates to structs. Brittle, but it is a toy app anyways.
(Normally use django to deal with models and migrations, but wanted to do something different)
I gave it a good go to use mongo and firestore for a few projects, but after a year or two of experimenting I'll be sticking to SQL based DBs unless there are super clear and obvious benefits to using a document based model.
* meaning, when there's enough code that depends on it that changing it would require some planning
Though most of the time, in that situation, I would pull it out.
But I tend to just use Django. Every time I try piecing together the parts (ex FastAPI, Pydantic, Alembic, etc) I reach a point where I realize I’m recreating a half baked Django, and kick myself for not starting with Django in the first place.