Sand is not typically safe for rabbits at all unfortunately
it sounds like a good idea but isn’t at all. Due to consumption automatically your rabbit will nibble at it to catch a taste which is normal behaviour (it can cause major digestive issues, GI status etc), respiratory problems for example due to the dust of it.. if it does get into the eyes or nose irritation @ it’s finest, not sanitary for them especially if they potty in there. I can go on and on. Your best option is using natural things like shredded cardboard, I use carefresh bedding (bedding is a good choice as well) my buns love to dig in it and it’s okay if they do ingest a little of it. Stay away from the sand. Hope this helps.