Lots of media devices that don't have AV1 decoders tend to have issues decoding high resolution AV1 in real time so you either get pauses to buffer or dropped frames.
Yes but if it says "NUC" I doubt you'll have that issue.
I think you're seriously underestimating how expensive software decoding AV1 is!
I'm not even entirely sure whether a NUC could decode 4K AV1 in software in real-time.
I have a 13 year old CPU that needs 2 cores to decode 4K AV1. It's not that bad.
Maybe not 4K at 60fps but that's not a lot of content.