p.1 #1 · Can a Godox flash trigger control all Godox flash
Can a Godox flash trigger, say, XProN or X1T-N for Nikon, control all Godox flashes regardless of the flash's camera system? ie. Can a XProN, mounted on a Nikon body, control a remote V350O Godox flash made for Olympus? If yes, can it still do TTL or is it manual only?
p.1 #3 · Can a Godox flash trigger control all Godox flash
That's my understanding. The transmitter translates the Nikon speak or Olympus speak or Fuji speak into Godox speak. The flashes understand and react to the Godox speak.
p.1 #6 · Can a Godox flash trigger control all Godox flash
You may have to update the firmware on the Godox flash to have TTL and HSS work but with the latest firmware, when you use another camera system all you have to change is the transmitter.
There may be hotshoe differences -- for example, you can't use a Sony flash on a Nikon hotshoe but off camera, it works fine.
p.1 #8 · Can a Godox flash trigger control all Godox flash
I have a xpro trigger for Nikon, one receiver for a SB800, a TT685 N and F (Nikon/Fuji). Everything works perfect. I got the Fuji because it was $25 on eBay (lucky deal). TTL works perfect on every one of those flashes. With the SB800 I also get additional control when I use the cameras built in control and the trigger (non documented but great bonus if you play with it).
What I don't know is if I can control, say, a Canon speed light with a godox receiver and have it integrate with TTL with the other speed lights. If it can that be great and I don't see any reason why it would not.
Also, I can use my Godox Fuji flash with the Nikons in manual mode (just triggering the flash with the center pin). I can also use the xpro-n trigger on my Fuji without any TTL... used center pin to trigger.