The Main Idea
It would solve tons of problems if it was possible to develop games for GB(A) in gameEditor. Like the development for Android, and the Android SDK. Plus, GB(A) emulators are on many platforms.
GameEditor C/C++
Let's make it clear that we all know that GE uses C/C++. And believe it or not, GB(A) games are too. Quite often if not always. Either way, it's possible to be done in C/C++. But GE would make that easier.
Gameboy Cartridges
If it can be written to a cartridge, that would be totally recreational, because GB(A) is outdated. There would be more hope to just build it for an emulator (in GBA/GBC) format.
Gameboy Controls
If there was a way for exporting to be done, GP2X should work fine. But the problem would come in at testing a game - let's say, on a Windows PC. Because it doesn't have the certain buttons necessary for input/output for a GB(A). But that would be fixed by writing a code that recognizes both keys. Or exporting the game first THEN testing it through an emulator.
Graphics & Resolution
This shouldn't be a problem. Being that GE has many screen resolutions, and if I'm not mistaken, customizable, the game shouldn't have that problem. But again, GP2X should work (if the GP2X thing isn't being mistaken by the actual keyboard thing - if not mistaken all together). GBA games are compatible with 32bit PNG graphics so, hooray!
The Bottom Line
So thanks if you can help. If there is a way, consider the premises en bolded.
If there isn't, and the only reasons are listed in bold up above or for another reason, then I'm puzzled because if those things in bold can not be done, then that's a waste of capabilities. But I do hate to picture a game not working because of certain actor types in the game. Again, any bit of information, will help.