To get the Nintendo Pro Controller working for Steam, follow these steps:
Only steam itself supports the pro controller, they wrote their own drivers for it.
source @Brice#6819 on Discord
Set Steam Input Per-Game Setting to Forced Off to stop steam from passing your DS4 controller through as it's own Xinput and just let KQB detect it as a DS4 controller
source @Leix#7916 on Discord
If you run into other issues, please join the Discord and make a post in #questions or #feedback-general.