Nice read. I run 5-6 projects on Supabase currently. I have also run into the local development / migration obstacles. It's otherwise been pretty great for our needs
Currently all supabase db and migration commands support --db-url flag [1] which allows you to point the CLI to any Postgres database by a connection string.
If there's any use case I missed, please feel free to open a GitHub issue and I will look into it promptly.