Sorry, I wanted to reword my comment to be shorter but say the same thing basically.

Nothing worked. In hindsight, maybe the Mac would've been ok-ish if I'd used Chrome Remote Desktop to help whenever she had issues, which had fewer pitfalls than the other screen sharing options I tried. Last one I remember was Teamviewer, which broke cause her friend "fixed her computer by removing junk" like that, but it also had other issues before.