As
@Scott P mentioned Supabase is a Postgres database with an API and other backend features on top of it. It also has some client libraries to simplify working with it in your framework. If you scan the main
https://supabase.com/ page you can get a pretty good idea of what it is about.
But it likely can handle what you want to do (you mentioned a schedule app). It is not a framework though and you will have to write your app to use the auth features and database features of Supabase as appropriate.