I think webOS has been open sourced and there used to be some effort [1] to port it to devices starting with the nexus 4/5. Seems the effort is still decently active with a release just last week[2]

[1]: https://en.wikipedia.org/wiki/LuneOS

[2]: https://pivotce.com/2018/11/28/luneos-november-stable-releas...