If you would just stick to playing games on the Quest 2/3 directly that should be fine. The Quest 2 can run basic games, so it does limit you a bit. For example VR Chat has some worlds with too many assets that are not playable on the Quest 2 directly. From what I remember you would be limited to Meta’s store though.
Unfortunately VR seems to be a niche thing so I doubt this will get a lot of priority on Linux.
Yup YouTube makes it very easy to receive money from adds and people that have YouTube premium. Having a YouTube premium subscription means that you are at least supporting the creator of every video that you watch a little bit (from what I can find 55% of what you pay is going to the creators). Yes YouTube takes quite a large cut, but video hosting in high quality costs a lot of money.
I think it will be very hard to do this on a decentralised platform. People don’t trust just anyone with their money, so it could lead to people abandoning smaller servers and you can be sure that bad actors would pop up and try to abuse the system. And even if you do this the right way, you would have to build this system entirely before you can convince creators to move to this platform.
It will also be really hard to offer the same quality and reliability that YouTube offers, without taking a larger cut than the 45% that YouTube takes. Hosting a large video platform is expensive, and many of the Fediverse users are anti-adds and will run an add-blocker and maybe even sponsor-blocker.