Interesting discovery: https://wonderos.org/ .

What I gather from a quick overview:

• system design “laboratory” for UX innovations beyond current OS user interface designs
• core idea of “items”/itemized UI as small composable UI components that OS graphical layer can arrange at user’s will(no separation of applications between windows requiring context switching or limited colocation and integration). Applications are responsible for rendering those components, but OS/user decides where.

See also from author: https://alexanderobenauer.com/