Yes this is in the character blueprint as it is the place that receives the input. You can probably move some of the logic in the wheelchair but you will have to start from the character or the controller as they handle your keyboard.
The first red node is just something I had handy from the first person example. It is equivalent to your G key.
Here:
Again, and I can’t stress this enough, get your wheelchair properly. This blueprint will grab it regardless where in the world it is located.
Also this BP will release the object when the G is no longer pressed. You might want to change that.