Unfortunately, as is usual for them (edit: and it makes sense; I'm not blaming them), the parts and upgrade kits aren't available for ordering (edit: or pre-ordering) yet, and likely won't be for some time, until the actual laptops are shipping. But yes, this is amazing, and the new pieces are not things I was expecting from them. As soon as it's available, I'll be taking my relatively recent AMD mainboard and putting it in a new chassis+battery+keyboard+speakers+touchpad, possibly skipping the display (I don't care much about a touchscreen, but I do care about display quality, so I'll wait for comparisons to the current 2.8k display). My laptop will, at that point, be almost entirely in a Ship of Theseus situation: I think that only the bezel and some of the expansion cards will be from the original, first-generation laptop I bought from them. That mainboard runs a number of services for me, along with an older display. A second, newer one is waiting for RAM to be a reasonable price (since the RAM it was using is now on my current mainboard); I had planned to use it for some of my research, but maybe I'll end up putting it into this older chassis and have a spare laptop again.
That all this is possible is wonderful, and a credit to them in staying true to their stated ideals.