I got it working by adding --/renderer/multiGpu/enabled=false at startup, thanks for the pointer in the right direction!
As per the logs, it seems to have choked on the secondary GPU, event though I read it would automatically skip non-RTX hardware by default, and the logs showed the RTX to be the “Active” one.
Here’s the corresponding docs where I found the commandline arg in case anyone else runs into this:
https://docs.omniverse.nvidia.com/app_code/prod_materials-and-rendering/manual.html