http://uwb25d43nnzerbozmtviwn7unn7ku226tpsjyhy5n4st5cf3d4mtflqd.onion/posts/grapheneos/index.html
Standard Android smartphones have Google baked into them (for example, Google Play Services has irrevocable access to your files, call logs, location, etc.). GrapheneOS removes all Google apps and services by default, uses hardware-based security to make it far more difficult to bypass the disk encryption, and it is significantly hardened against hacking.