I've smoothed several out several table saws with honing stones. Use
oil and a couple of stones of different thicknesses. Rub by hand in a
circular motion, creating a slurry. Wood blocks with sandpaper are too
soft in my opinion. Once the wood dents or debris gets betwee the
block and paper then you're not using a flat surface anymore.

You could also take it to a machine shop and have them run an end mill
or fly cutter over it. Being a Ryobi, I'd suspect that your top is
aluminum though. I wouldn't try to mill that at a shop. It can be
done but the top is probably thin. I use car wax on my saw and have a
friend who uses rain-x.