In theory commercially we can accept up to 10cm of dry snow.
But when you look into it the friction coeffcient can vary between 0.1 and all the way up to 1.40.
Given a good length of runway your main issues aren't what you would expect. The biggest danger is xwinds when you are on the ground and getting blown off the side.
So I am not suprised your landing distances are shorter than grass.
But I suspect the expert on this is as usual Pilot DAR