The most promising method is or Lantus' Halo CE for Android (an old, unofficial source port from 2013). These use reverse-engineered code to run the original assets. However, they are outdated, crash often, and require you to manually copy map files from a PC copy of Halo: CE.
If you want to beat The Silent Cartographer on your lunch break, here is the exact setup I use: halo combat evolved apk android
Be extremely cautious of websites offering a direct "Halo CE APK." Because there is no official mobile version, these files are often: The most promising method is or Lantus' Halo