Whay do you mean? Like a debian system + NixOS VM?
Discussion
Nix project started as a package manager ( like APT) .. so Nix is flagship package manager .. biggest set of packages ..
NixOS is a diteo based on Debian .. natively driven through Nix Package Manage ( instead of APT )
So before you venture into nixOS .. I highly recommend acquaint your self with nix package manager .. you can use nix on any Linux distro or Mac