Now that’s an idea I hadn’t considered - a powerbank to charge the USBridge. Do you know what current it needs to deliver - from memory not much other than startup (but get that wrong and I’ll be rebuilding it!).
I have 2 powerbanks lying around so easy to try them if they can provide enough juice. Oh and how long between charges for you? I think mine are 20,000mAh capacity, so obviously I’d get less.
Phil