All this is speculation, anyway; only the Larian dev team know enough about their game to tell us how easy or difficult a desktop Linux port would be.
Converting Stadia version to proper desktop Linux version is a lot easier than converting DX11 or DX12 version to Vulkan itself. Bethesda developers gave a few talks about Stadia development and pointed that out.
Dealing with specific memory issues and etc. could be needed to address wider variety of desktop use cases. But it's not super hard to do for those who are already familiar with Vulkan development.