I'd say your chances are very good. Even their high end rackmount models work with the usbhid-ups driver. Don't think they would change things up in this regard since they would also need to change their software.

I've never had a Cyberpower that hasn't worked just find with but. Nuts a PITA to configure, but other than that it likes Cyberpower. I have that model - without the 3-R - and it's great.

I would be extremely surprised if the 3-R version didn't work. With Cyberpower, I don't even bother to look up compatability. I bought 3 EC850LCDs blind, for the router and a couple other servers around the house. They all came up just fine.

Inspired by yesterday's Jeff Geerling video, were we?

I would be shocked if it didn't work. It is up to you if it's worth the risk to try it and see!

The xxx3 seems to be a slightly upgraded version that adds a colour LCD and USB charging ports. Apart from that, it seems to have the same features as the one without the 3. And the -R seems to indicate a "restored"/"refurbished" model.

Not that I'm some kind of UPS expert, but I've never found a UPS that NUT wasn't compatible with.

Well what's the delta between the two? Just searching adding the "-R" seems to be a lesser version with things like missing ports. Logic says if you're using NUT that it would at least have network or serial to communicate with something, and it would work just fine, but look for reviews and figure out what the difference is since it's not listed as a defined product model on the Cyberpower pages.