Supabase is an open source Firebase alternative. Start your project with a Postgres database, Authentication, instant APIs, Edge Functions, Realtime subscriptions, and Storage.

Supabase

Have you seen count used in the select fields documented or used somewhere?  I don't recall seeing that as an option.  You probably have to use a view or rpc call unless you have seen this somewhere.

but i figured since this probably is transformed into sql that would be possible

No. PostgREST which handles the API only supports a subset of what you can do in sql for performance, security and probably just code complexity reasons.

does the supabase client include an sql client?