Yes, you can self host and everything is open source (including the Dashboard[0]). Everything is either MIT, Apache2, or PostgreSQL licensed.
> difference between Supabase open-source and the paid versions
On the paid version we handle some of additional database management (like daily backups, PITR, etc). These are technically available for self-hosting too, because the database is just a Postgres database, but I point it out here because it's not something you'll get "out of the box" from the Docker setup.
Our philosophy with open source is "offer everything" and then charge for usage. There aren't any features completely gated. Our Enterprise plan just adds additional SLAs and support packages for our cloud platform.
In addition to the self-hosting docs you've linked, in our GitHub you can find the Docker files[0] and some community-developed self-hosting strategies [2]
EDIT: Googling around yields a somewhat hostile discussion from last year: https://news.ycombinator.com/item?id=26637360
... but it looks like you _can_ self-host? https://supabase.com/docs/guides/hosting/docker