I used to house my buns on vinyl because indeed some buns might eat the fleece. My buns ate the loose fleece blanket I gave them so I figure’d they’d have a go at fleece bedding too. However, I’ve been housing my buns on fleece for 2 weeks now and they leave it alone. I think it’s because they can’t dig it into a pile because I tucked the edges under their flooring. They dig at it every now and then and nip at it (and then realize it’s stuck I guess :’) ) and then leave it be. I would say just try it, you will notice soon enough if your bun is ok with it or not.
What to put in the pen to keep your bun entertained is depends on your bun. Some buns like plastic balls, some like throw toys, some like chew toys and others ignore everything. I would maybe get a plastic ball and a chewable ball first to see if your bun is interested in plastic toys at all and if he likes chewing the chewable ball. If he chews it, you know you could buy more chew toys.
Avoid things with honey, seeds and whatnot as those can upset bunny tummy, but if it’s hay based/wood based it’s fine to give.