With only needing the Intel FSP, does that disable the Intel ME? And what other peripherals need closed firmware?
You also are not here:
https://www.coreboot.org/users.html
I say that because I have been in the market for a laptop, and I am looking for a free(dom) based laptop. I looked there and it led me down the path of a Purism laptop.
Have you also thought about adding some sort of hardware kill switches for Cameras/microphones/Radios?