Eh up chuck
You can use any finish on it once it's dry. The glue is under the rawhide so won't be affected by a water based poly. Also the water evaporates so nay problemo.
Try using a spray car laquer, dries in 20 mins per coat and looks good once done.
The rawhide strips shouldn't just be butted up against each other but feathered into each other. Eg. soak them and dry them flattened out then file/sand them to feather edges and then overlap the feathered edges. You may find it a lot easier to ask nicely if anyone on here has any dear rawhide for sale/trade as the dog chew stuff is a little thick?