Not surprised about the proprietary battery plug. This isn't a charger, it's the devices only power supply. If the power sags or glitches, you get a crash, and

Not surprised about the proprietary battery plug. This isn't a charger, it's the devices only power supply. If the power sags or glitches, you get a crash, and the other side has to deal with a lot of variation in the current pulled. Letting people use random power banks wouldn't work well, and constraining yourself to USB-C for what is essentially the connection between your device's battery and the device itself sounds painful.