The software that runs on mobile Linux is the same that runs on desktop arm64 Linux, minus a few mobile-specific components packaged by postmarketOS/etc. Minus the few mobile-specific components (modem drivers, userland components like the virtual keyboard and window manager), the software is very well tested and used regularly. Only thing I’m sketched about is the sim card, which has quite a lot of control over the device from what I was told. It’s not like non-linux phones are any safer from this though; if anything they’re more likely to be targeted by any hardware vulnerabilities/backdoors due to being more popular devices.