I just found out that @ahcorde submitted Install ros2 on Ubuntu with pixi by ahcorde · Pull Request #5833 · ros2/ros2_documentation · GitHub and Pixi config file to install ros2 on Ubuntu by ahcorde · Pull Request #1721 · ros2/ros2 · GitHub to install ROS 2 on Ubuntu with Pixi. The instructions still use colcon for building ROS 2, which would be a separate discussion, but a great first step nonetheless.