If it’s true that the app needs to be connected to the internet for reconfiguring your controller, that’s really stupid. Hopefully they’re just saying that you need to be connected to the internet to download the app.
Though honestly, I wish Microsoft would just cut down the proprietary aspect of game controllers and make it all open source. I’d love for a Gullikit equivalent to the series controller with Hall effect thumbsticks. Then game developers would just have to put limits on what inputs are capable in competitive games to prevent custom modded controllers from breaking games.