We do them in karate sometimes. A wooden floor is probably the best option, rather than a carpet. The coarse fibers will aggravate the skin of your knuckles, or at least that’s what I find. Concrete or paving slabs (as I once did at home) are a decidedly bad idea. Most people find they can do fewer knuckle pushups than they can open palm pushups. For some reason. This exercise has been known to cause problems in the knuckle joint. People who do a lot of knuckle conditioning tend to end up with arthritis.
So all in all, I’d hazard a guess that you’d be better off with the pushup bars as suggested above. You can also use hex dumbells in the same way. I have a major boner for hex dumbbells. They just look so cool.