While an official port does not exist, the gaming community has created impressive fan projects and sandbox alternatives that mimic the GMod experience on mobile. If you want to download a sandbox game, look for these legitimate projects on trusted platforms like the Google Play Store: 1. Simple Sandbox 2
If you already own GMod on Steam, you can stream the game directly to your Android device. This is the only way to play the official game on a phone. gmod android port download link