I use this for my drone without the insert. I bought it for a GoPro which now collects dust, so I took out the inserts and put in the Tello and accessories. I carry Tello on the left side, Xiaomi repeater and bigger solar powerbank on the right side. Batteries are on sides of the Tello. Cables, props and 3 batteries charger is in the net on the lid. I don't use controller, but if I got smaller powerbank without the solar panel, controller would probably fit on right side of mine. Only downside is that it is not very secure and it can move if you shake it.
But you can find cases exactly made for Tello with controller, like this one. It is more expensive and still doesn't have place for powerbank. So it will mainly depend on the size of your powerbank, when it comes to choosing the case.