Since MacOS no longer supports OpenGL and Linux relies more and more on Vulkan, it might not be that easy anymore. But only Larian can judge that. A native Linux port would be fantastic.
Regardless of that, D:OS2 seems to run quite well under Proton. It has silver on ProtonDB and many Linux users seem to be happy with this solution:
https://www.protondb.com/app/435150The problem is: this isn't official. Maybe D:OS2 could get on Valve's white list? It already has titles like Nier: Automata, which runs very nicely on Proton. I have had very good experiences with Proton so far. I haven't tried D:OS2 yet. I haven't bought it yet. I am a bit unsure because it is not officially supported.