I see how SQLite being just a file makes it easy to do lots of things from a developer point of view. However, I'm looking at this from a "business owner" point of view, at which point it's not just a file, it's my clients data. That's a bit scary for me, so I have a bias for "reassuring stuff" like managed databases with automated backups. This is why I'm looking for more info on "the hard parts" of managing SQLite. I'm conscious that this bias might not be based on reality, especially since I don't know well MySQL or PostgreSQL, especially how they store data on files. But as a relatively young developer, I've heard a lot that "data should go in the database" and databases are big scary things that should be managed by people with lots of experience and knowlegde in that role.
I'll take a look at fly.io, thanks.