Lots of trying out ideas, focusing on the body this time.
In the end, my main focus ended up being how to best implement the wing and how it would fly with it.
To simplify my thoughts: I don't know if it makes much sense to have the arm bend like a bird wing, while having the body of a mammal, with the hand of a kangaroo. I don't want the body to get too long, but still have enough surface between the legs to generate enough upswing.
I tried to read up on how animal shoulders work, but it's a lot of knowledge to digest.