AFAIK OxygenOS is more about optimization than about security, but I might be wrong. There's CopperheadOS and also SilentOS, both Android-based, the formed bei

AFAIK OxygenOS is more about optimization than about security, but I might be wrong. There's CopperheadOS and also SilentOS, both Android-based, the formed being open source and working on the Nexus phone. Don't ask me about how good they are or how they compare to each-other though. In general, there are vast differences between devices - various vendors often add various applications that you might easily put into the malware category. I'd say that if Android, go with Nexus phone.