Switch Pro rumors are nothing new, as they've been floating around for a couple of years now. Every once in awhile they pick up steam, and that's exactly what happened with the reveal of Monster Hunter Rise.
Nintendo has paired Monster Hunter games with hardware revamps before, and some think that's exactly what Nintendo and Capcom have planned for Rise. That's in part due to history, and also because some found Monster Hunter Rise to be too impressive visually for the standard Switch.
In an interview with Eurogamer, Capcom's Ryōzō Tsujimoto is asked about the gameplay footage seen so far, and the potential for a Switch revamp. You can see his full response below.
(Monster Hunter Rise) was all running on Switch - everything you saw at TGS. ...obviously we have no idea whatsoever what the plans would be in that direction (a new/revamped Switch), but even at the moment you actually have two different Switch hardwares you're targeting - you've got the the original Switch which has the docking mode, so that's something we've already borne in mind to make sure that the game isn't making any undue assumptions on the hardware owned by the player. As to those kind of plans on Nintendo's side, we can't speak to those at all. We're trying to make the game work as best as it can on whichever Switch you have