Nice idea, but I don't see how Xbox players wouldn't be completely dominated in this scenario.
I play PUBG (not implying you don't), and I can see it working OK. This is not a 'gun play centered game', its more positioning and strategy. TTK is also pretty high making most gun fights more about movement than aim. No need for aim assist here, probably better without it.
In those situations where you can settle down, zoom in, and head shot someone, a controller will work just as well. Most gun battles are at range in this..and many times the person you are shooting at doesn't have a clue they are in your cross hairs / they don't see you / have no clue where they are getting hit from (the game needs some subtle directional indicators for sound at least, IRL you'd hear and know where it was coming from but thats another point for another day)
Also, coming from a background of consoles more than PC, there are definitley some gun fights I would have won if i was using a CONTROLLER instead of KBM. My fingers still betray me sometimes.
There arent many inputs either, inventory can be done with a stick and a fast cursor or short cuts (just like right click does).
Now, if it was something like CSGO or OW, then I'd say good luck to controller users.