All of the cool development-related Nix things like pinning a project to known-good library versions (for regression tests or otherwise) don't really need you to run NixOS. If you like NixOS then it's a perfectly usable distro for development work, but all of the powers come from Nix itself, and that can be installed anywhere you feel comfortable with.
The only real pro of running full NixOS is that everything you work on will test a relatively uncommon *nix setup by its nature. Things like developer-only scripts with hardcoded #!/bin/bash shebangs are more likely to break on NixOS than they would on a conventional Linux distro with Nix installed. That's something potentially worth fixing as it might also hurt the developer experience on *BSD/Mac systems.