I used FCP on an M1 Air with _8gb_ to edit 4K videos for over a year. Assuming you have enough fast storage (or are happy to use a proxy workflow), it certainly can be done, although everyone’s workflow is different. Assuming no storage speed bottleneck, timeline scrubbing was smooth up to about 2x forward or backward, from memory - after that you hit decoder limits. Proxy workflow gets around that too, though. Render times on even the M1 were a big jump over Intel chips. If Apple has a 2-week return policy where you are, why not give a 16gb M2 Air a try and see if it meets your particular needs?

What’s a proxy workflow in this context?

Do the editing on proxy clips that have been rendered at a lower quality so the performance cost is significantly reduced.

Thanks, that's great to know. It sounds like it will be a huge step up from my 2014 MBP which grinds to a virtual halt on 4k. For that reason I've limited myself to 1080 for now, but when I upgrade I figure I should step up.

I plan on getting a re-furb, not sure if I can return one of those...

You can, but honestly, if you can afford 24GB, go for it. Remember that unlike in the Intel days, the GPU uses main memory for its RAM. (Well, I guess integrated Intel GPUs did some of that, too.) That can be painful when you've got a few clips in the timeline and some plug-in wants to have multiple copies of each frame for doing its processing. (Like it applies a blur, then mixes that with the original, or whatever.) I have a 16GB MacMini I sometimes edit video on, and it works, but there are times when things get choppy/slow. I also have a Studio with 64GB, and it's smooth as butter. (I mean it's possible to load it up so it slows down, but it takes a lot more to do so.)

I don't do this specifically, but if you can go without $2k for a few weeks you can take advantage of Apple's permissive return policy and just demo for IIRC 14 days.