Yes. But as another poster mentioned, can your grandmother setup (and also maintain) a windows computer, keeping it free from malware etc.? I posit no.

Can they maintain and keep a Mac (no installation needed) updated and free from malware? Updates sure, but malware free? I posit no.

Now to Linux. My small sample size evidence is that more than 5+ yrs ago, I set up my GPs with Linux Mint, and they use it without any issues. Since they don’t have root, and it’s Linux, the malware footprint is near enough to zero making them as safe as possible from anything bad. It also helps to educate them about not trusting unsolicited emails, etc.—-But, although related, is for a diff discussion.

When I periodically visit them, I check that updates are done.

I’ve had zero complaints from them.

So yes… grandparents can not only use, but love Linux!

Can your grandmother set up any other computer?

What is a computer nowadays anyway? It's just a web browser for most people.

EDIT: A colleague of mine had his grandmother on Linux back in 2010. He remote connected to update it and keep things in order. He said it was the easiest to maintain.

Certainly yes. I have installed her one. Took me 15 minutes to install. Everything works.

With most distros, Linux is no more difficult to install, configure, and use than Windows is.