IT WORKED.
I did film the moment of truth, but all that happened was the same thing as before, the power button lit up for as long as I held it down with my finger. So I stopped filming, and then several seconds later, I heard what sounds like a fairly whiny unhealthy fan spin up, and I looked down and saw the obnoxiously RGB Corsair keyboard lit up.
I assumed nothing was happening, so didn't hold Cmd+Alt+O+F long enough to get into open firmware and boot via USB, so that's why I'm just getting the icon, I assume.
Actually now that I think of it, wouldn't it be a question mark icon if it were a matter of an HDD with no bootable OS? It might just be slowly booting off the USB as we speak cause I'm still seeing smiley Finder folder icon. ???
