In my opinion, those warnings are not used to help users but to shame developpers for not trully sandboxing and verifying their apps. Developpers know that having this warning will decrease the number of users downloading it. The goal in the long run is to improve app sandboxing and security.
RedoxOS, an open source operating system written in Rust that aims to improve correctness and safety by picking up innovations made by experimental operating systems over the years while not reinventing the wheel and trying to be source compatible with Linux.
QubesOS, the most secure open source operating system making it easy to use security by virtualisation, splitting your activities, peripherals, drivers into different virtual machines.
If you’re interested in Meshtastic, take a look at Reticulum : https://reticulum.network/