Did they show any GPU benchmarks or otherwise give an indication that the Linux support will be relatively full-featured? Because what I've seen so far is just a Geekbench CPU score on Linux that was significantly higher than the Windows score because fan control wasn't working on Linux.
Dunno myself, but I do remember that the company behind the initial chip design was targeting the server market, so that’s probably the reason for Linux support. I kinda doubt that the GPU has any Linux support, it’s just a regular Qualcomm developed GPU.
By upstream support, do you mean the relevant device trees and drivers have been contributed to the kernel already? (I'm asking because there are some listed here https://kernelnewbies.org/LinuxChanges#Linux_6.5.ARM but they seem to be a different model)