And there's no clear value-add here. I am particularly adamant that Linux needs to move towards reproducibility yesterday, since the ability to inject spyware in Linux is first and foremost a process risk.
Those distributions are making huge efforts in keeping a core that is 100% reproducible, working upstream to fix issues, and providing reporting and tests tools to detect regressions (for example [2])
This is why a fork is usually a bad approach.
[1] https://reproducible-builds.org/who/projects/ [2] https://en.opensuse.org/openSUSE:Reproducible_Builds