I can't personally, but I've installed/set up Linux systems for quite a lot of older people, and I think only one of them ever uses the terminal for anything. The rest just... use the computer.
On the whole, they're pretty much just using Libreoffice, Firefox and a few other bits these days. If something needs the terminal to fix, we're already past the point where they've phoned me to pop round and fix it.
These used to be Ubuntu systems, but I switched them all to Mint after having endless Snap permission problems with printers, USB sticks and other peripherals. Once up and running, it's pretty low maintenance.
I guess they don't need to use the terminal, because I'll go and do it if it's necessary - but we are looking at once every few years. Not a lot of tech support needed.
On my own machine, I probably use the terminal every day.
Interestingly enough, Xfce4 has a kiosk mode. You could build a custom desktop for them and restrict changes. You then could do mass updates with Ansible or Saltstack
It's a good plan for a more professional setup, but in this distinctly unprofessional setup, if I did it remotely, I wouldn't get my chat and a cup of tea and biscuit :)