http://secure45nbquibuw6thmenrfamhobdkkrllgxrtayn4sgmnexremexyd.onion/linux-phones.html
The hardware itself lacks many modern security features too, such as proper verified boot , a hardware-backed keystore (some PGP smartcard is not equivalent) and more. Although one way to fix the issues in software would be to install a more sane OS like Android or its derivatives,
such as GrapheneOS, if support for the hardware was added.