EdgeDB and EdgeQL are doing something in this direction. SQL with GraphQL for joining solves some problems. Built on top of PSQL.

I think PSQL can only take you so far though, I think we will move to something new eventually.

For most apps you want to watch a query for changes. SQL is a pain for that. If you can get inside the query tree though, you can do some caching and materialization to help. And I want to run my db in my browser too.