Yes, they are easy to port a lot of the time. Especially now because you can use DXVK to translate DirectX calls into Vulkan, so you don't need to write a Vulkan renderer. Input is sometimes a trickier one to deal with but a lot of the time games are using cross-platform libraries for that already!

Despite all this the Unity engine has spotty Linux support. Some games run better under Wine vs. Unity's native Linux builds. It's Vulkan renderer has had a memory leak for a while now. Input has randomly decided to double keypresses on some distros.

> Personally I prefer to use their built-in stuff as much as possible.

Why? Avalonia is a spiritual successor to WPF but FOSS and cross-platform.