
It not being available to purchase directly from Steam means you have to get it from a 3rd party reseller, or order it to an address in an officially supported country and forward it from there yourself, both of which are generally more expensive than what steam is offering. The cheapest price I can find for a Steam Deck OLED in my country is a solid 20% more expensive than the price Steam lists on their website.

My point is that literally nobody has been looking at obfuscated code for at least 5 years by now. All the toolchains automatically handle de- and reobfuscation transparently to the point that nobody has to think about it anymore unless maybe you are one of the like 3 people who is actually maintaining the classloading stage of a modloader, or if you are manually writing a bytecode transformer (which almost nobody has needed to do for years either, ever since tools like Mixin entered the scene).
For 99.9% of the modding community, and this includes most optimization mods, the only thing that is going to change is everyone deletes a line or two from their build.gradle and continues about their day.
As far as reporting things to Mojang: again, nothing changes here either, everyone who has ever set up a mod dev environment already has a copy of the deobfuscated source code on their computer, which is the only thing they are looking at when inspecting the minecraft source code or making changes to it. There have been reports on the issue tracker with actual suggested code changes basically since the issue tracker became a thing.

This doesn’t really change too much for the modding scene, it just allows the deobfuscation step to be skipped when setting up a dev environment. Mojang has already been providing official deobfuscation mappings for years, and before that we had community-made ones which were already pretty great.
There are already plenty of mods which drastically overhaul how major parts of the game work to get better performance, and there are some projects like Gregtech: New Horizons and CleanroomMC which have pretty much completely torn apart and rebuilt the game on older versions from before official deobfuscation mappings were even available.

That’s not going to go away by switching to AMD or some ARM implementation, they all have their own equivalent. Maybe if you’re running some fully libre open-source RISC-V chip, but those are currently nowhere near capable of competing on the big stage for anything other than embedded/hobbyist stuff.
I’m sure you can also stream to it over a conventional wifi connection as well, the point of the dongle is so that they can guarantee a direct connection with lower latency and on a dedicated radio frequency to avoid interference, which is especially for non-techies who don’t know what they’re doing and just expect stuff to work out-of-the-box. The headset is just running SteamOS and has a regular wifi antenna, so I see no reason why you couldn’t stream to it using plain old Steam Link or whatever if you already know your connection can handle it.