I would do plywood with laminate flooring over it. That’s what most people here have done. You can also put wood trim along the edges of the shelf so that he doesn’t chew the edge of the laminate flooring

This is how I first had Mimzy’s cage. It’s hard board cut to size, sitting on top of an NIC grid shelf. There is self adhesive laminate flooring on top of the hard board flooring, & then trim along the edges.

The board was only temporary though, I now use birch plywood covered with adhesive laminate flooring, although plywood is more expensive than hard board, it’s also more sturdy/long lasting.
It’s basically the same concept as above except non-treated plywood as the base, then self adhesive laminate flooring, & trim drilled on the edges. I also put caulk where the trim meets the floor so that any kind of pee/liquid doesn’t drip through. If you choose to caulk it, just be sure not to let your bunny anywhere near the new floor until the caulk is dry & make sure the caulk is smoothed out enough that your bunny can’t grab hold & chew it.

There’s also some videos on youtube showing you how to build a bunny cage & a lot of them will show you how they laminate the floor for them