> Giving direct access to your database is fast but leads to very strong data coupling.

Or you could just give "direct" access to (a DB role that only has been granted SELECT on) a single schema within your database, entirely consisting of views. Then you've got a stable data-access API that you can iterate your data model behind, with nothing more than your DB itself.

(And you don't need to put much thought into setting it up, if you don't want to; your stable schema-API-layer can just start off as a bunch of views with 1:1 relationships to your real tables, which each just "SELECT * FROM their_underlying_table".)