Most emulators nowadays have their source code nicely open, and the vast majority of them fully support Linux too but Cemu has been a bit of a holdout. Not for long though.
On their official roadmap, which many people emailed in excitedly, they put up their plans and who can blame people for being excited on this? Scrolling down a bit, a Linux port is clearly mentioned. It has been an "ongoing side-project" already but quite slow as it was low-priority and it depended on other things being done. The good news is that they say it's about "70%" of the way there already. Having Linux support of course will also be great for the Steam Deck, since it comes with SteamOS 3 (based on Arch Linux).
Just as exciting is the plan for Cemu to go open source! This is planned to happen in 2022 and going open source was "originally promised". No exact ETA on when they plan to do it, as they will also be restructuring the source code. They've been continuing to rewrite various parts of the C code into much newer C++20/23. They also plan to move from Visual Studio to cmake, which is another step towards supporting more operating systems.
So they have a lot of work ahead but it will be worth it. Having it properly open source will ensure it's preservation, just like what it does for old hardware like the Wii U.