I noticed that my kde desktop environment, installed from the devuan installer
via tasksel, had the option to "Set date and time automatically" was greyed
out.
This is most likely due to the fact that on default debian desktop
installations the ability to set time via ntp is provided by systemd. therefor
it also affects some (or all) other desktop environments.
In order to have a fully functional desktop environment without systemd either
task-desktop, task-kde-desktop or desktop-base should contain an ntp client.
As a workaround: manually install ntpd or ntpdate or...