It’s almost like you could check out the linked campaign and answer that question with a couple of minutes reading.

The money goes to supporting pixelfed, loops and sup development, with the goal being financing full time development for the entire team.

Unfortunately, the only hardware component you can actually download is RAM. And increased hardware prices are going to be the primary cost factor.

I cant speak to CoD specifically, but being able to locate opponents, shots, activity etc by sound is a massive advantage in many multiplayer shooters. I can personally vouch for its relevance in CS, Apex Legends, Arma 2&3, The Finals, DayZ, and Battlefield.

For your viewing pleasure I leave you with this Viva La Dirt League skit: https://youtu.be/sC8qtyGoGZw