They both allow you to deploy and update a highly customized OS across many potentially different machines.
Gentoo has cflags and cross-building
Nix has Nix configs
I somewhat disagree about the stability. Maybe it’s no longer the case, but i used gentoo for a few years in the 2010s and it was always stable for me. A buggy upstream release of a package could be a problem in theory, but if that were to happen you can generally roll back the package and mask it from updates for a while. I never ended up needing to do that. However i agree that stability seems to be a high priority for Nix devs.
They both allow you to deploy and update a highly customized OS across many potentially different machines.
Gentoo has cflags and cross-building
Nix has Nix configs
I somewhat disagree about the stability. Maybe it’s no longer the case, but i used gentoo for a few years in the 2010s and it was always stable for me. A buggy upstream release of a package could be a problem in theory, but if that were to happen you can generally roll back the package and mask it from updates for a while. I never ended up needing to do that. However i agree that stability seems to be a high priority for Nix devs.