I dual boot OpenBSD on it, and it's been doing fine. The out of the box experience is pretty bare although the default window manager cwm is surprisingly nice once you get to know it. Note that apmd, the power management daemon used to manage CPU speed and low-battery suspend, is not enabled by default. The high-DPI screen required some adjustments in Xresources (I haven't dared try a multi-monitor, mixed DPI setup).
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.
No wifi driver for Framework 16. Was fun installing (and surprisingly quick) and playing around a little. But unfortunately that's a dealbreaker for me.
Let's see, System 76, previously Dell and Samsung.
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".
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.