I just used the i686-linux steps here:

https://github.com/fgsfdsfgs/perfect_dark

As with most of these decomps there is no copyrighted material included in the link and you have to provide your own ROM (and a very specific version of it) in order to build and get it to work.

After that I believe I just copied the folders to the Deck, mapped it as a non-Steam game, added updated artwork with the steamgriddb plugin etc.

I might have messed with the controls a bit but I don’t recall. There is probably a more detailed Steamdeck-specific guide somewhere if you care to dig.

Can confirm that 60fps Perfect Dark goes hard on the SteamDeck.