Will there be a 4th part? If so, what will it be about? An idea may be to add authentication using Supabase (GoTrue) to the API, so from the client-side, the user can log in using Supabase and the access token that he obtains, use it with FastAPI. That way the user can use all the Supabase services from the client-side and for specific things the API, all with the same access token.