Finally!

I can run Odyssey 2 on my Android phone without using either that Videopac emulator that did not work very well or emulation on top of emulation with DosBOX, which didn't work very well either.

Retroarch has a core for the Odyssey 2 that really works. Full speed on Attack of the Timelord and JG Munchkin; I'm playing on my phone with a bluetooth wrap around controller. Demon Attack also works great (except for the bug in O2EM which sometimes messes with collision detection). The KC games played decently, though for some weird reason Pick Axe Pete alone demonstrated slow down. Turtles ran fine, but I'm not able to do the precisely timed movements well with my bluetooth stick.

The biggest problem - it won't switch to the other joystick for UFO, Alien Invaders, etc. I tried every controller setting, nothing so far...