Sorry to necro this, but opjose could change the words he chose to "defend" non-Windows platforms.
By now it is 2021 and RealFlight still has to come to other platforms, which is sad.
WINE is not an emulator, it is a wrapper and works great. Even back in 2015 you could already run DirectX applications, the only thing holding RealFlight back from running has nothing todo with "Windows API" bollox. It is copy protection.
Now we even have DirectX to Vulkan translation in realtime, making even Windows games run better on Windows.
I run all my games on Linux, the only games that fail to run usually deploy some form of failing DRM and I would gladly pay for the game/simulator if it ran. Triple A titles run no problem and have been running on Linux for years now.