If you see posts that go into Linux phones and how they are dealing with the issues Android solves to make them viable, I'd love to hear about them. I'm not an expert or actively interested in researching this space right now. From memory and past conversations with others, Android is far ahead of anything in Linux when it comes to the CPU schedulers and how they deal with core spin ups for power management and advanced core multi core asymmetry. Linux has no such capability for similar asymmetry, or last I checked. The SELinux and PAM are far more advanced than any typical distro too.
As far as I know, a phone is nothing like a desktop. The cellular modem and undocumented SoC are like being connected to some random shady public WiFi and having your financials in plain text on the system. There is no way to know with certainty what is or is not connected.