There is currently no official version of Garry's Mod (GMod) for Android.
I get it. You want to play GMod on the bus. But downloading a random APK from a forum or file-sharing site is one of the most dangerous things you can do with an Android device. gmod android port download link
When downloading APK files from third-party sources, there's always a risk of malware or modified files. Be cautious and only download from reputable sources like APKPure or APKMirror. Also, keep in mind that these ports might not be optimized for Android or may contain bugs. There is currently no official version of Garry's