Puppy Linux UEFI (alternatives?)

So, in the past, I used to make a bit of money fixing up comps for folks.

With slightly trickier cases, I used to boot up puppy Linux to check the more essential hardwares (and if it booted, back up essential files for the customer). My students are now asking how to manage similar things.

Alas, puppy is no good for a modern system, as it really does not like UEFI boot. I was wondering if anyone can recommend an alternative.

I'm looking for a very lightweight gui os I that can run some hardware diagnostic tools, runs on a wide range of hardware, that is easy enough to set up on a pen for novice users.