I saw that you didn’t want to use a 3rd party provider, but why not stick a git repo on your VPS (which you are trusting with your data today) and use that to coordinate syncs between your client devices?
I don't think you really get it. Git is distributed. There's no need for "a git server". You already have a machine on which you host the SQL database, you can just use that as yet another git remote.
Thanks for the reply. I do agree with sibling comment from tasuki that I think you’re missing the simpler solution of plain git repos to solve “owning your own data in a future-proof manner”.
If you’re not trying to coordinate work among multiple people, and aren’t trying to enforce a single source of truth with code, you don’t _need_ “git server” software. You just need a git repository (folder & file structure) in a location that you consider to be your source of truth.
I’m not trying to convince you to change it now, especially if you’re happy with what you have, but I would suggest reading some (or all) of https://git-scm.com/book/en/v2
I think the first ~4 subsections of chapter 4 cover what I & tasuki were suggesting could be sufficient for you. If you’re the type of engineer to read through the code of your data storage layer, I think you’d find Chapter 10 (Git Internals) interesting, because it can demystify git. I enjoyed the whole book.
As with any engineering project, I see lots of questions about your choices, and I applaud you for sticking around. I would make very different decisions than you, based on your stated priorities, but that’s okay.
I saw that you didn’t want to use a 3rd party provider, but why not stick a git repo on your VPS (which you are trusting with your data today) and use that to coordinate syncs between your client devices?