I don't suspect memblocks would be so much of an issue.
More like anything that tries to draw to the display or read touches (or keyboard).
An API would be okay even if it has such commands, as long as you don't try to use them.
As for telling if they do, look at the commands they offer. If a command says something like 'OpenWindow' or 'WriteTextToScreen' (totally fictitious commands, sort of, just theoretical), then those commands wouldn't work in an AppGameKit environment.
In theory, there are things you might be able to do to add to the display, but it would require playing with some of the AppGameKit core files to allow it, as well as the Java setup stuff (for Android) and the iOS core code (for iOS). Not generally recommended unless you are a real expert in those platforms.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master