It is not really a backend when it does not involve business logic but just an access layer for the DB. It is pretty much a client server model.
XgeneCloud makes it really simple to add business logic for generated APIs (REST and GraphQL both) over any SQL databases.
We just launched this week [2]
[1] : https://github.com/xgenecloud/xgenecloud
[2] : https://news.ycombinator.com/item?id=23466782
Website : https://xgenecloud.com
(disclaimer: founder here)