Theoretically you can still get WPF running on another OS, but you'd have to do it the same way that WSL gets an Ubuntu userland running on Linux: You introduce

Theoretically you can still get WPF running on another OS, but you'd have to do it the same way that WSL gets an Ubuntu userland running on Linux: You introduce a compatibility layer that it runs on top of. I think I'd prefer that approach, anyway - I'd guess it's cleaner and ultimately more maintainable than introducing a whole bunch of conditional logic for handling all the cross-platform issues into an already complicated piece of software.