While true, people should pay attention that WinRT, the technology infrastructure for UWP, nowadays lives in Win32 and is what is powering anything CoPilot+ PC, Windows ML, the Windows Terminal rewrite, new Explorer extensions, updated context menu on Windows 11,....
It is a moving target, Proton is mostly stuck on Windows XP world, before most new APIs started being a mix of COM and WinRT.
Even if that isn't the case, almost no company would bother with GNU/Linux to develop with Win32, instead of Windows, Visual Studio, business as usual.
It's not a moving target. Proton and Wine have shown it can be achieved with greater comparability than even what Microsoft offers.