[yencabulator]

See also ghOSt by Google (2021):

https://storage.googleapis.com/pub-tools-public-publication-...

https://github.com/google/ghost-userspace

https://github.com/google/ghost-kernel

[vient]

Also sched-ext which seems close to be mainlined and is already a default scheduler in CachyOS:

https://github.com/sched-ext/scx