I've been experimenting with NextCloud + CODE (Collabora Online Developer Edition) - https://www.collaboraoffice.com/releases-en/collabora-online-2-1-1-rele… - it's early days, but it's already getting pretty close to what Google Docs/Sheets/Presentation can do. It builds on LibreOffice, but provides a browser-based interface, and concurrent collaborative editing...
I'm not convinced it's "FOSS" - it might be gratis, but it's not libre (I don't think the source is available) - although I'd love to be proven wrong :)
I've been experimenting with NextCloud + CODE (Collabora Online Developer Edition) - https://www.collaboraoffice.com/releases-en/collabora-online-2-1-1-rele… - it's early days, but it's already getting pretty close to what Google Docs/Sheets/Presentation can do. It builds on LibreOffice, but provides a browser-based interface, and concurrent collaborative editing...