I agree native window and Wine will always have a layer for complexity .because of this complexity it sometimes causes a performance or bug issue. The proton project looks very promising and works well so far.
https://github.com/ValveSoftware/Proton
example of proton performance seems good
https://www.forbes.com/sites/jasonevangelho/2019/09/12/far-cry-new-dawn-never--released-for-linux-but-its-matching-windows-10-performance-anyway/#6568759f121f
Also having Affinity on Linux would expand the market and respect from the Linux community. as I mentioned before maybe having a snap package for Ubuntu base system would be a better approach since this distro is well known with ordinary and beginner users. Ubuntu also is being used by an enterprise company for their workstation. Short term I understand that Seif doesn't have it on Linux, but it would be very beneficial for them, in the long run, to have it cross-platform, so users can shift when needed when the market or situation changes. All artist tools should be modulated, in my opinion, but I can be wrong.
One final thought, maybe a valuable solution is to port it on Steam?