> And then they will depend on your API data schema...
+100 to this
+100 to this
The DB can do everything can’t seem to understand this, for some reason.
That depends on the DB's foreign table support, or equivalent, if it has it. It's certainly not categorically impossible with a DB.
Of course, merging different backends can not be done on the backend. Either you add a layer or you do it on the client.