They don’t cover aspects of a desktop environment that are not related to using Mir. Missing functionality includes: integrating into the system for screen locking & suspend, policy kit integration, internationalization, etc.
To use egmde as your desktop, select it when logging in, to run it on your desktop run "egmde".
Egmde can be configured by editing ~/.config/egmde.config or on the commandline. Options are listed with:
$ egmde --help
There's more about customizing the appearance of egmde on the Ubuntu discourse:
Snaps are applications packaged with all their dependencies to run on all popular Linux distributions from a single build. They update automatically and roll back gracefully.
Snaps are discoverable and installable from the Snap Store, an app store with an audience of millions.
Snap is available for Linux Mint 18.2 (Sonya), Linux Mint 18.3 (Sylvia), Linux Mint 19 (Tara), Linux Mint 19.1 (Tessa) and the latest release, Linux Mint 20 (Ulyana).
You can find out which version of Linux Mint you’re running by opening System info from the Preferences menu.
On Linux Mint 20, /etc/apt/preferences.d/nosnap.pref needs to be removed before Snap can be installed. This can be accomplished from the command line: