I sell coreboot, and coreboot accessories. With Debian Linux. These are secure machines, and coreboot is well-audited.

These computers are free as in freedom, right down to the boot firmware, booting linux/bsd on the bare metal:

My web shop is here:
https://minifree.org/

I'm the author of osboot, the version of coreboot that comes installed. It replaces proprietary UEFI firmware, and has many advanced features that you can learn about here:

https://osboot.org/