I recently tried to get my mom to use the PWA of Word online, and she said it was "worse" than the desktop version but refused to elaborate as to why.
I know I sound like I'm being harsh on my parents, but it's not like they're stupid or anything. They have spent the last 30+ years using Windows and Microsoft Office, I don't blame them for relying on the tools that they have spent the last three decades learning; I use command line tools that have existed longer than I have [1]. I do understand the stubbornness even if it does drive me a little crazy.
[1] Yes I know that GCC and Emacs and tar and grep have gotten updates since they've been released, but so has Windows.
You're right, Office is where you will struggle.
I managed to get Winboat working on my NixOS laptop, so it's possible that if I set that up they could deal with it.
Seems like you have it all figured out though, I think I’ve shared enough help good luck.