For PC, it is not xinput or anything that most games outside of Steam will recognize, but Steam will handle it just fine and if you setup a non-Steam game to launch through Steam then Steam will convert it to xinput for the game to understand.
For deck, it’s fantastic, like a Xbox or Switch controller but with a touchpad. So depending on the game you could have it as a mouse, or three simple buttons(left, right, middle) or my personal favorite as a wheel of options, so you can stack as many as you want there(I find 6 to be the limit of my comfort).
I’ve had mixed luck configuring the mute button(bottom of controller, toggles an orange light), for some games it works great for one more button, for others it doesn’t seem to recognize it, unsure why. This is literally the only downside I’ve seen with it and I use it a ton to play a variety of games
I’m afraid I don’t know Playnite, googling it didn’t tell me much as far as compatability. You’ll have to try and see with that, it may be a game by game basis of whether it works or Playnite may have its own solution?
I used to dual boot windows on my MacBook but stopped bothering when I got the Steam deck so I don’t really PC game anymore and never did with the ps5 controller.