I put my mom on Ubuntu with KDE 10 years ago. I had far less problems with her on Linux than I ever did with Vista and 7. It got to the point she was calling me multiple times a week.
I didn’t have to but I did one Ubuntu reinstall in that entire time only because I made /boot the default partition size at installation and years later it filled up constantly. I got sick of going over there to clean it up and it coincided with her getting a new computer.
My mom installed printer drivers, and Cisco VPN software from run packages instead of apt and set up multi- monitors on her own after I taught her how to use the terminal, so it’s possible for the elderly.