Gift him a Starsector code or share your own if already have one.
Gift any super moddable games he likes. If he enjoys Bethesda games on consoles, he will definitely love PC only mods. Also explain to him what Big Picture Mode on Steam is. I wish I knew it existed when I started. Get the same console experience and seamless controller integration even if the game doesn't officially support it.
Edit: Also any super pretty games would probably be a nice gift. Cyberpunk 2077 was one of the first I installed. Really nice realizing how much better looking games can be with a powerful computer.