System76 Developing "COSMIC" Desktop Environment For Pop!_OS
While System76 has long been a supporter of GNOME, with the changes around GNOME 40 they have decided instead they will be moving to their own GNOME-based desktop environment. COSMIC will make its debut in Pop!_OS 21.04 due out this June.
System76 describes their new desktop effort, "We’re providing a honed desktop user experience in Pop!_OS through our GNOME-based desktop environment: COSMIC. It’s a refined solution that makes the desktop easier to use, yet more powerful and efficient for our users through customization. The new designs are developed from extensive testing and user feedback since the Pop!_OS 20.04 release, and are currently being further refined in their testing phase."
COSMIC in their context stands for the "Computer Operating System Main Interface Components." Compared to GNOME's Activities Overview they have separated it into two distinct views (Workspaces and Applications), the super key will activate the launcher by default, an option to have a dock, and support for both mouse-driven and keyboard-driven workflows.
More details on the in-development COSMIC desktop via the System76 blog.