System76 also ships laptops with Coreboot (https://system76.com/laptops).
Their laptops are a newer generation than the Librems and they ship with support for EFI boot such as systemd-boot, etc. I don’t think the Librems support EFI boot.
The ME region in the system76 laptops is disabled with the hap bit set which is working on the newer iterations of ME based upon this pull request (https://github.com/corna/me_cleaner/pull/282) though its not yet implemented in a release.
The thing you would be missing with a system76 laptop though is PureBoot and the integration with the Librem Key.
They currently offer two models with support for Coreboot.