So a Switch 2 game where you walk around the real world and catch Pokemon? I see a bunch of issues with it:

• The S2 does not have mobile Internet, so they would need to preload maps of the entire world and put out constant game patches to keep them current. Any multiplayer content will only be playable when the player is home (or by a Wi-Fi hotspot).
• The S2 does not have GPS. Would they track location by polling the joycon accelerometer every second and moving the player character 2 inches down the street? You would be to start every play session from a known location and keep the S2 running for the entire play session. Also, the longer you play, the more the errors in your location will add up.
• The S2 does not have a rear camera, so you cannot do AR, only a fantasy background.