As primary Arch Linux developer Levente Polyak discloses in the announcement post, "Valve is generously providing backing for two critical projects that will have a huge impact on our distribution: a build service infrastructure and a secure signing enclave. By supporting work on a freelance basis for these topics, Valve enables us to work on them without being limited solely by the free time of our volunteers."
Polyak continues, "This opportunity allows us to address some of the biggest outstanding challenges we have been facing for a while. The collaboration will speed up the progress that would otherwise take much longer for us to achieve, and will ultimately unblock us from finally pursuing some of our planned endeavors [...] We believe this collaboration will greatly benefit Arch Linux, and are looking forward to share further development on the mailing list as work progresses."
These quotes go to show how bigger corporations like Valve can still be a helpful, desirable influence in the FOSS (Free and Open Source Software) community. While the rules of FOSS dictate that Valve was under no obligation whatsoever to give back to the community in any way, it's had a great track record so far through Proton and is now directly funding the continued development of Arch Linux, which forms the foundation of its own SteamOS 3 operating system. It's true that volunteers in FOSS make that part of the tech world go round, but it's always nice when these projects can actually afford to pay people to get the work that needs to be done for the rest of our enjoyment.
I'll wait and see what comes of it. Valve have been singlehandedly responsible for evolving Linux gaming by leaps and bounds, to the point where the only real hurdle right now is anti-cheat compatibility.
Their direct collaboration with Arch is massive for that reason alone
They have a battleeye proton build that devs can choose to ship with if you use that, but for some reason most (including GTA V online) just... Decide not to use it.
"some reason" = anticheats are less effective on Linux, and publishers rather have fewer Linux players than more cheaters.