This is the android front-end to GBCC, a cross-platform Game Boy and Game Boy Color emulator written in C with a focus on accuracy. See the main repository for details.
You can get gbcc on Google Play.
Debug packages are generated on each commit. To download them, navigate to the actions tab (you'll need to be logged in to GitHub to do this). Select the latest "Build Packages" job that succeeded, and look for the artifacts dropdown.
I'll write up instructions on this at some point, but it's pretty much just install the Android SDK & NDK, clone this repo recursively, and then run
./gradlew buildThis will generate the apks in app/build/outputs/apk/.