This https://github.com/elogind/elogind/blob/8e778a23e1c13bd3613c9c40a53291d476ae8c2a/src/login/logind.conf.in seems to indicate that elogind supports HandleLidSwitchExternalPower.
This https://guix.gnu.org/manual/en/html_node/Desktop-Services.html seems to indicate that guix does not support that setting.
