This. I have been running it the same way for some time now. Even if you change something on one machine and something else on another nextcloud will just happily inform you of the conflict and then you can open both databases and cherry pick. Never had corruption issues.
Moved my sister to Ubuntu a while ago aside from the occasional support call everything works quite well.
As for my mom, I sat her down way back and told her she needed to move off of Windows XP (support was running out). I explained to her that she could learn Windows 7 and eventually 10 (8 was already a known dud by then) or she could switch to a “Traditional” desktop paradigm that resembled XP closely where she’d only had to relearn once and then keep running it forever, so I moved her to MATE.
While most issues she had with incompatibilities could be solved (and often remotely by me just via ssh) there was one MFP that just wouldn’t scan properly (I’ve scoured the web for guides and sane drivers etc.) in the end I set up a Dual boot Windows (with a nice "switch to Windows " script right in the pinned apps) just so she could scan from there (scans automatically saved on a NAS share that was also available in Linux so she could use the scanned documents there). These days the MFP died and she got a new one that will actually scan in Linux but I kept the dual boot just in case (though I doubt she ever uses it).