Why would it need USB 3.2 gen 2 for a controller? I don't even need that port for my Oculus Q2. Is there any evidence that USB impacts BT input lag? What about those PCIE Wifi/BT combo things?
Looking at it specs, USB 3.2 gen 2 available in 3 USBs of the PS5 offer way faster speed and way less latency compared to the previous USB versions used in PS4 or Series X|S, so it should offer less input lag when playing wired. Sony didn't provide details, but since DualSense uses USB-C I assume it uses the USB 3.2 gen 2 available in 3 ports of the consoles instead of USB 2.0 available in one of its ports (that may be to ensure 100% compatibility with certain PS4 legacy accesories and controllers even if USB 3.2 gen 2 is supposed to be BC with previous versions).
Looking at its specs, Blueetoth 5.1 is way faster and has way less latency than previous versions, so it should have way less input lag when playing wireless compared to previous Bluetooth versions like the one seen in DualShock 4 or XBO controller (MS didn't provide details about the Series X|S controller but it should use the same wireless than in XBO). Sony didn't provide details but I assume that if the console supports Bluetooth 5.1 it's for DualSense.
The input lag changes for each controller. I think it's pretty fair to assume that if a controller uses a USB or BT technology that offers way faster speeds and less latency it will have a better input lag, specially when connected to a device that supports it. Input lag is key for competitive play, and also for streaming games both via Remote Play or from the could with PS Now or similar services, or even for VR.
Here you have some controller input lag comparisions:
https://inputlag.science/controller/results
RocketLeague/comments/8wvf9u
Most controllers until now did use USB 2.0 because it's what standard console pads (like DS4) did use. So for these 'old' controlers you don't get an advantage when connecting the to a USB with higher specs, same goes with Bluetooth.
But if DualSense uses USB 3.2 gen 2 and Bluetooth 5.1 as seems to be the case, if you want to test its input lag unleashing all its potential, you'll need USB 3.2 gen 2 for wired and Bluetooth 5.1 for wireless.