https://noflux.nostr.technology/, for example, uses a Postgres database and that's so awful because it's meant to be used by a single person in a desktop home machine. I even tried to switch it to SQLite because it would be a strict improvement (https://github.com/fiatjaf/narr uses it luckily) but couldn't (yet) because SQL is so bad it's not even standard among all databases (and everybody knows that, but it's impossible to do anything about it).
I also tried to use https://pglite.dev/, but it didn't have easy to use Go bindings apparently.
