Linux for the Elderly?

I work as a volunteer assisting elderly shut-ins with learning to use a computer. Instead of the troublesome and expensive Windows and Apple systems, which they can't afford anyway, I would like to set them up with a low-cost laptop with a simplified, standardized Linux-based system so they can do basic chores like letter writing, checkbook balancing and sometimes photo collections or email. Since these users are absolute technophobes, the obvious first requirements would be:

1) No command lines;
2) No passwords (must be secure system);
3) No antivirus requiring updates;
4) No complex desktop or taskbar (3 - 4 icons max);
5) No ability to disturb settings by accidental keystrokes or mouse clicks.

I have been using Linux Mint since January 2020, and have set up one simplified Linux system for an elderly person who was already familiar with computers. She greatly prefers this to Windows and Apple systems she has used before.

If someone has done this before for a new computer user, my questions would be:

1) How did it work out?
2) What Linux version and setup did you use?
3) What software did you use?
4) How did you secure the computer for this kind of user environment?

Any advice from someone's experience would be appreciated.

Thanks,
Ron Purcell