If we use the GPIO to power the board, could we use the USB OTG for something like one of these?
https://smile.amazon.co.uk/dp/B07DVCVVZG/
I mean, I would guess that there’s still no USB3, but that’s OK as the connections will just work at 2.0. I plan to use this all with the MEGA PI case, and if it passes through enough power to the RADXA ZERO I think it could be an amazing option. As I would be able to place a USB-C hub with ethernet on the main port, and BOOM. 
Anyway, I guess what I’m asking is … If I use GPIO 2 will it provide as much power to the board as the USB-C input?
EDIT - It’s a week later … and … well … I’m powering my board using the RetroFlag Mega-Pi case, currently, and it played back a hard file over a USB GB ethernet connection on a powered USB hub in the main USB-C port, with a simple OTG cable connecting a wireless keyboard in the power port. So it looks good!