This thread kind of blew up and I simultaneously got rather busy. I discussed the topic a bit elsewhere with @mjcarroll and have decided the best way to go forward is for me to work on solving the hurdles with ergonomically using nix to build a ros project (containing projects that are built with ament, setuptools, nix, etc) and publicly release a demonstration. It’s possible this will be tested on an autonomous vehicle before the end of the year.
Edit: adding the following because I think it’s relevant
The reason a better build or dependency management system is necessary, whether it’s nix, bazel, or conda, is that rosdep on top of Ubuntu is not guaranteed to be able to install a package’s dependencies and has no way of resolving version conflicts. This makes it unusable for some projects. I believe nix specifically has numerous benefits (as outlined in the previous posts), and intend to make a demonstration for its use, as something tangible to play around with would help with demonstrations and discussions.