Porting from Stadia to desktop Linux is not as straight forward as some have stated here.
All of those issues you mentioned are pretty trivial to solve. So it is a lot easier than making a Windows version work on Linux. Besides, if they are not going to use a custom engine, and will go with something like Unreal (is there any info on that actually?), then Linux support will be provided by the engine to begin with.
I'm holding out hope they'll work with the Proton team to offer a great Proton solution which already sees phenomenal performance with some titles.
Wine is an option, but for game that already plans Stadia release, requiring to use Wine to run it on Linux is quite a sour result. I'd call such cases Vinegar
Another alternative is developing an open source Stadia shim for Desktop Linux, as in it translates input and output to and from the desktop environment (and display server) which ultimately will result in close to zero performance loss.
That's something I mentioned as well. Google probably won't be Linux gaming friendly enough to implement such shim themselves, but someone else can, for example making SDL plugin that translates Stadia SDK input code into SDL proper. That should even further reduce the effort of making a desktop Linux release from a Stadia one.