I uploaded a version with the Steam API calls disabled, but I haven't had a chance to test it yet.
So, it was still freezing, but I've managed to have a litttle bit more luck running it?
Here's a player.log from a sucessful run:
vs a current unsuccessful one:
https://pastebin.com/n0quF2TC
The difference really seems to be in that VK_ERROR_DEVICE_LOST line, and I can't quite figure out what's caused that. Tried glancing at a couple things, like alt-tabbing from the game or making sure the HMD was not in sleep mode, but no luck.
This seems the right time to note that I'm using nvidia-driver-440 on my 980 Ti, specifically apt pulls the version as 440.82+really.440.64-0ubuntu6 amd64. Juuuust in case that helps.
Does the game crash at that point or does it hang? I was dumb/lazy and never made it so that loading the game didn't block the main thread so when you launch the game it sits there for about a minute loading/initializing everything. It might be that the vulkan driver thinks it's lost the device, but it's actually just taking forever to respond.
I was able to repro the hang that you're seeing as well as the occasional run. So I tried to update to 440, but the latest I could see was 430. I updated to that and then Steam decided that it needed a specific version of libgl. So then I tried upgrading Steam from apt-get and now it kind of looks like it's trying to build Steam from source...I'll keep trying.