It's possible to use your steam deck as a controller on your pc. You can use steam link, but if your WiFi isn't very good there will be problems, or virtualhere. I haven't tried virtualhere but I have heard that it is good, unfortunately, the only good guide I found for it is on reddit :(

https://www.reddit.com/r/SteamDeck/comments/v22ddf/guide_how_to_use_your_deck_as_a_steam_input/