Wanna make an FPS controller that takes this version forward

I really really really love this video by Pyott Design, it’s a masterclass in designing and building ideas. And I’m already making a version that is purely from scavenged existing parts. I want to make a proper pcb and learn to design the boards myself, so the prototypes are less bulky. I already have the CAD skillset and ideation process handled, but I need a way to get my hands on just the mouse sensor (internet says scavenge it off a gaming mouse thats broken), a recommendation for a decent solder for noobs, and some guidance on how I would go about designing an arduino FPS controller.

P.S.: He has a second video, but he kind of goes back to a steam controller esque gyro and trackpad setup that’s not nearly as interesting (in my opinion).