Copperhead OS
– De-googled OS with managed cryptographically secure vault, security, and enterprise support
– Runs on latest Pixel devices
– A bit pricey starting at $250 for a 3 month subscription

GrapheneOS
– Free as in Beer
– Fully Open Source project – Formerly CopperheadOS
– Easy web install on latest Pixel Devices
– Privacy by Default
– Sandboxed Google Play (optional)
– Guide: Graphene OS + Pixel 3a Install Process

CalyxOS
– Free as in Beer
– Based on Android Open Source Project (AOSP)
– Uses microG instead of sandboxed Google Play (optional)
– Pre-installed with a plethora of privacy tools (YMMV)

More information: Citadel Dispatch e0.3.4 – mobile phone privacy with @sethforprivacy