https://github.com/SeleniumHQ/selenium/blob/886cdf5397481ebebe02310b8b3aa07f374695ef/dotnet/src/webdriver/Interactions/PointerInputDevice.cs#L74C5-L74C5

MouseButton enum contains Touch member, it seems really strange.

According spec https://www.w3.org/TR/webdriver2/#pointer-input-source Pointer input source has subtypes, like Mouse or Pen. It seems that PointerInputSource should be abstract class, and derived MouseInputSource and PenInputSource.