@Zanthuros i’m trying to do the same thing for the camera, i believe the rotation is handled in the ninja camera manager.
i don’t know about the mesh rotation yet,
for the camera rotation, you can get the cross product of the controller right vector with the character capsule up vector to to find the forward vector at the new angle
you can use “make rotation from axes XY” X is the new cross product vector, and Y is the right vector of the controller
then you have to get the difference between the previous rotation and the new rotation you just calculated
add the result rotation to your current controller rotation.
add me on discord IdirFETT#6735 if you have it, 2 minds are better than one alone
EDIT: maybe this is just for pitch only !!