I dont know if TiGRA is german. I searched but couldnt find their website.
They way I see it this is quite a universal case. Not integrated to their other products. Yes they do have a battery that fits their cases. But you can use any other battery that fits aswell. About the jumper cables. A 2.5mm DC Plug is nothing special. You could use this cabe to wire it to you dynamo or an bigger battery in your bikes side pockets for example.
But thanks for the Arkon hint. I will check them out.