From what I understand...
The right USB C port is a somewhat limited capability USB C OTG port. I suspect that a person may need one of these to use it in host mode:
https://www.amazon.com/UGREEN-Adapter-Samsu...s/dp/B0744DYN9TThough there are reports from people who have theirs that say they can connect one, but only one, device at a time through the right USB C port. I.e. even with a hub it only sees one device. There is something else funky going on there too, though. The Planet Computers USB C to HDMI connector is supposed to ONLY work in the right USB port. I'm uncertain of whether the Gemini can charge from the right port.
The left USB C port also has some funky stuff going on. It appears that it is either a charge port or host. There are reports that using the Planet Computers USB C to USB 3.0 & ethernet hub works - but that it cannot charge while that is connected.
Which leads me to a curious point.
It appears that the Gemini in 'desktop mode', connected to it's USB C hub on the left for keyboard, mouse and ethernet and connected to the monitor via it's USB C to HDMI adapter on the right is left with no way to charge or maintain charge while in this mode. Someone please test this and figure out a way to prove just how wrong I am.
I should be receiving my Gemini, charger, hub and HDMI adapter in another week or two.