FITTEVER - Fitness at your fingertips. Live fitness classes.
Growl for Windows - Growl for Windows is a Windows-compatible version of https://alternativeto.
Classtra - Single platform for virtual, in-person, hybrid activities
Notify OSD - Canonicals on-screen-display notification agent, implementing the freedesktop.
SocialBoat.live - A real life Fitness game
Notifu - Notifu, a free open source pop-up balloon utility