elementary OS
elementary OS is an Ubuntu-based desktop distribution. Some of its more interesting features include a custom desktop environment called Pantheon and many custom apps including Photos, Music, Videos, Calendar, Terminal, Files, and more.
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NebiOS
NebiOS is an Ubuntu-based desktop Linux distribution with a custom Wayland compositor called NebiDE (based on Wayfire). It features various user interface enhancements, an initial setup module called OOBE, the NebiOS App Runtime (napp-runtime) portable application format with bubblewrap containerization, improved gaming performance with Steam Proton integration, a kernel switcher for easy multi-kernel installation, and the Wine compatibility layer for running some Windows applications.