I'm a Gentoo dev and work at CERN since a while. Of course I jokingly suggested that to my colleagues. I think it could actually work pretty well, though. Many physicists use Gentoo.
We run most things on Alma Linux, but there's also RedHat in the mix.
A good intersection of CERN and Gentoo is EESSI. They use CVMFS, which is a FUSE filesystem used for software distribution from CERN, and Gentoo as part of their software stack. See links below for more info: