That's a tradeoff that sometimes makes sense. MICROS~1 SQL Server heavily leans into the 'use specific features extensively', and countless applications on it consist mainly of stored procedures. It does however cause a lock-in that might not be attractive, your customers might be sensitive to what database engine you run their stuff on and then you need to figure out the common ground between two or more alternatives and build your application in that space.

It's not as uncommon as one might think, one of the big products in public sector services where I live offers both SQL Server and Oracle as persistence layer so they can't push logic into stored procedures or similar techniques.

But just sketching out some schemas and booting PostgREST might be good enough for forever, if that's the case, go for it. As for ORM:s, I kind of like how Ecto in Elixir settings does things, it solves a few tedious things like validation and 'hydration', and has a macro DSL for generating SQL with concise expressions.