The Framework Laptop DIY Edition comes with no OS installed, so you can bring your own. We're working with a couple of popular distributions on compatibility checks and updates. The pre-built Framework Laptops do come with Windows 10, though you can install anything you'd like too.
Is this going to happen before the preorders open? I love the concept and if it had anything approaching System76's first-class support of linux that would make a strong offering that much better. I don't mean going so far as to bankroll a whole new distro, "just" things actually working right.
While you're here, are there any new answers to your conversation with Luis Rossmann[1] WRT availability of schematics?
I love what you guys are trying to do and hope you succeed in a big way!
Does it run 100% free software? Will it be certified with "Respects Your Freedom" certification by the FSF?