It seems to me the steam deck already meets this regulation, or would with very minimal change. It does not say you need to have an access door like gamboys had. It just says the battery needs to be easily replaceable with commonly available tools (or included tools). To replace the steam decks battery you just need a size 0 Phillips screwdriver and something to pop it open like a guitar pick or a credit card. You would easily be able to get all the tools you need at any hardware store.