I have a Logitech G923 for XBox, which is recognised in the game as such but It’s really difficult to setup because it lists button numbers instead of using the symbols on the buttons, e.g. A, B, X, Y, LSB, etc.
This is something that Dirt 5 and Dirt Rally 2.0 both manage, so don’t see any reason why Forza Motorsport couldn’t do the same.