For whatever it's worth giving people a desktop or laptop computer that is a bare bones linux install and desktop environment will also prevent old people from screwing up a computer. Literally 99% of what they are ever going to do is inside a browser, and will function just fine inside of Firefox and/or Chromium as their user interface to the computer.

It's highly unlikely that an older person is going to successfully find, download and install a malicious .deb file, or follow the instructions to "copy this to clipboard and paste it with sudo" into their shell to compromise a linux machine.