But it’s good to know it’s future proof - ie if Supabase go out of business or a project takes off and I want to self host with all the good stuff then I can.

Until you dig into the code base and realise that self-hosting isn't something that is sustainable, at all, the minute you need a bug fixed, or run into a limitation, without the original authors or solution partners around to support your specific installation.

Most proprietary software shops tend to have business continuity clauses and solution partners. So, on-paper, one could self-host those too in case their business goes under.