GNOME is the default desktop of Chimera.
Installation
The easiest way is to use the base-desktop metapackage.
# apk add base-desktop
This adds gnome as well as several things a desktop session
will typically want, including graphics drivers.
It is possible to install those things individually for more
fine-grained control. Those users may also be interested in the
gnome-core package which only installs a relatively bare desktop
without auxiliary apps.
Starting
Keep in mind that GNOME requires elogind. In a typical setup, this
is enabled by default, i.e. requires explicit masking to avoid. You
do not need to manually enable elogind if you have not removed
its service link. Likewise, it requires dbus, both system and
session bus, see D-Bus.
Otherwise, you only have to start the gdm service. You can
enable it:
# dinitctl enable gdm
That will make it start on every boot. If you want to run it just once, you can also do:
# dinitctl start gdm
After that, you only need to log in and a desktop should come up.