Yes, I believe it is used to move to the next category within the menus. It is also used to bring up the voice call outs on the PS5. Yes, it makes stratagem selection a bit weird.
The future goal is for every controller to adopt a Steam input configuration. We all need dual track pads and 4 grip buttons. Virtual menus are awesome.
My biggest problems are aiming (I'm no good with the gyro yet) and being able to actually see targets. I don't play a lot of high action games on deck for this reason. But I played a couple lower difficulty rounds on the deck without fps problems.