I bought an iPad Pro 12.9 1st Gen. recently. It costed $150-ish and I’m very happy what I got for the price. So I’m considering to upgrade everyone to used iPad Pros. Most people don’t need a desktop operating system these days. The 1st Gen. iPad Pro won’t get past iPadOS 16, while the current is 17. But I believe it won’t be a problem for the next 5 to 10 years, which is plenty considering the price tag.
However, with Linux it’s much better software-wise: if you have relatively recent hardware, your support would be literally indefinite. I use 15 years old hardware and I can believe it would serve another 15 easily.
MacOS and iOS are specifically designed to be used by the average man, they're the right tool for this job.
Also: Do not make them use Linux unless you want your time spent as tech support to increase. Just don't.