How do the various BSDs run on framework laptops?
NetBSD seemed okay to but I've only used it a little bit. It actually set up X pretty well for the screen using some built in script with heuristics to determine font size from the screen metrics.
How is the battery life?
All the pretty much the smallest and lightest I could find. So not fantastic, but good enough. For me, battery life is much lower on the list than "small and lightweight" and "works well with Linux".