There are absolutely no dumb questions on the rabbit forum!
It would be super cute, but unfortunately, it's not safe. If you look at how a rabbit's spine curves in the opposite direction of the wheel surface they'd be running on, which would cause potential spinal issues from the rabbit flexing against its natural structure. Additionally, the gait of a rabbit is not smooth like a cat's, so the jolting and hopping would not only lead to being scary/uncomfortable for the rabbit but also setting up a situation where the wheel is moving faster than the rabbit's hopping and would likely lead to falling or the rabbit freaking out and hurting themself.
Hm, if it's really big and a safe design (no spokes or covered spokes), good flooring (capet, finely structured wood or whatever that gives good grip), I would say, why not. Didn't look much around, but some big diy cat wheels actually don't look that bad. As has been said above, there are arguments against it, imho mostly that rabbits don't run continuosly like mice, hamsters or cats, they don't have a "cruise-mode".
Since rabbits don't run for long times at a stretch (that's a valueable thing to know when it comes to herding escaped rabbits back home) I don't think that the issue with the curved floor (if the wheel is big) is really a serious problem, and they would learn quickly to deal with the inertia of the wheel (which should be as light as possible).
I wouldn't expect that it gets used much if they have enough space anyway (the wheel wouldn't be a replacement for floor space), maybe as long as they are young, but watching my rabbits grow up I get the impression that they soon move much more economic - to get somewhere, not so much to just run around or climb where no rabbit is supposed to go. Mine are rather big though, 10lbs range.
Would be a huge effort to build something suitable just to have it collecting dust, taking up space that could be used for a tunnel or something else. To build something I would deem ok would be a lot of work, expensive and not really worth the effort when I look at my rabbits, a good sized digging box might be a better exercise option (mine can dig their tunnels in the garden).
Buying something cheap wouldn't cut it, I think the worst design possible for a rabbit (or any other animal) wheel would be something like this: