There are always stories of people installing Linux on their parents computer to provide them a more secure and stable operating system, seems interesting to share experiences.
Edit: I’m assuming that parents are okay with the changes, or do not care. Obviously do not force anyone to switch OS if they don’t want to.
Debian is never a bad choice. Put some flatpaks there, backport some goodies, and install some kind of AnyDesk system. Put some KDE Plasma and they’ll think Windows finally runs well again.