README doesn't mention which Purism device this is for
It says:
System76 EC is a GPLv3 licensed embedded controller firmware for System76 laptops.
While it sure makes sense to credit System76 I think it's rather confusing to talk about System76 laptops although the firmware has been modified to work with Purism laptops.
Suggestion:
System76 EC is a GPLv3 licensed embedded controller firmware for System76 laptops. This repo contains a fork that has been modified to work on Purism's Librem series of laptops.
Also an indication how to make use of this repo on Purism devices by linking to any docs would make sense. The current link to the list of supported devices e.g. only links to System76 ones.