On the Guix days there was a session about running Guix on mobile phones. The notes will be published somewhere else. Don't know when and where yet.
Patch for chatty: http://issues.guix.gnu.org/issue/39312 On my personal (dirty) wip-librem5 branch on Gitlab.com is additionally software for the Librem5: https://gitlab.com/jonsger/Guix/commits/wip-librem5 phoc: successful build, somehow working phosh: successful build but not yet running purple-mm-sms: successful build, don't know if it's working as I lack modem for testing calls: not yet pushed, depends on updates (meson) who are not yet in master, but on core-updates
