Game gear should be possible, since after all it was just a hack of a mastersystem with a portable tv lcd screen. It even had an optional tv adapter which hooked into the screen line.
The Lynx screen however is directly controlled trough horizontal and vertical lines, and very hard to adept to anything else but the use in a Lynx.
If my memory serves me correctly the game gear screen was composite video.
Your best bet is to look into the GG screen and get some more specific specs on that.
