Like I said, the "database" is just a directory of files. You can use anything you want to keep it synced. I've used OneDrive, Dropbox and iCloud to sync mine.
I'd much prefer "syncing" to be something I set up once, and then forget about it.
If it is "anything I want to do to keep it synced", then I'll be half-assing it forever, losing notes and so forth. Already doing that, and the 500 pages of notes from 3 years ago on Google drive, to the "attach it in Gmail to a draft so I can look it over at home", hell even a few somewhere on iCloud. For some things others might be interested in, I've even got a few github gists.
This, for me, is a problem that is central to notes software. It might be the one problem that makes or breaks them. At least with the pricey subscription garbage apps, they know enough to know that I don't want to have to think about syncing.
The "database" is just a bunch of directories you can sync with any tool you want.