I had a few times on Windows with niche discontinued products. Not really a huge issue but it didn't work out of the box.

Here's your issue with Linux: You're expecting it to work identically as Windows does. They're different systems with different issues and solutions. I use Syncthing to sync my Keepass database updated between devices. It's very simple and easy to use.

Go into Linux unburdened with the expectation that everything should work the same and you'll have a better time. You have to acclimate to the new environment, but you did the same with Windows. You got used to how bad Windows is to use. Linux is generally easier, in my opinion, once you're used to it. It isn't Windows though so you have to learn new things.