Last time I tried Fallout 4 VR, it did accept keyboard input for certain controls (pressing E to activate things, for example; Not sure about movement via WASD), provided the game window has focus (which is also true for Skyrim VR).
Unfortunately, as you have noticed, Fallout 4 VR and Skyrim VR don't share the same VR implementation, in fact they don't share the same game engine version either.
There isn't a viable universal method to send emulated input to VR games as the platforms they use don't really support that (especially Oculus).