Yup, they are targeting people deep into the PCVR ecosystem. Index owners are their ideal customers. And now, people who previously purchased an Index and a Beyond, too.
The first one worked with some kernel patches, there is a Discord server (Linux Adventures in VR) with lots of information about getting various headsets running in Linux.
lvra.gitlab.io is a great source of info for vr on linux. The discord server you mentioned is also bridged to Matrix for those who don't want to use discord.
No they sell a generic facial unit that can work with almost anyone's face now and the IPD of the lenses is configurable, so you don't need a 3D scan of your face
If you are interested in Valve you might want to wait, rumor is we get at least an announcement very soon. I say this as someone that pre-order a Bigscreen Beyond 2 though, lol.