Although this article is about what new hardware got certified last month, I have never heard of this certification and think might have some potential.

According to OSHWA[0], they have 3,197 things certified. A bit squirly to get to, but here is their Open Source HW definition for the certification: https://oshwa.org/resources/open-source-hardware-definition/

[0] https://oshwa.org/