Can I allow users to fetch some tables only by id? I want to avoid a moment when someone will try to select all records from table. I dont see that option with RTL, is custom backend for that the only way?

You can use RLS for select set to false. Then create an rpc function which takes an id and returns a record for that row. The function needs to be set to security definer to skip RLS. There is an example in help the past day or two from same question.

Ohh that is so simple, thank you

Select only single row by id from table