What mystery code, or binary blobs remain with Purism laptops? Is there any concern with them?

Security is a game of depth, and Purism goes deeper than any manufacturer by avoiding blobs or mystery code in the top 4 layers of a computer: applications, operating system, kernel, and bootloader.

At the firmware level, we utilize Coreboot instead of a proprietary BIOS/UEFI, a huge advancement for current high-end laptops. Within coreboot there are still some binaries though.

https://puri.sm/road-to-fsf-ryf-endorsement-and-beyond/

We are “as close to free software foundations respects your freedom as possible with current Intel CPUs” but are spending real money to advance that toward complete binary freedom.