If I remember correctly, two Linux variants were on the list at one time.

They were:

Inspur K-UX (expired on 3 February 2019)

Huawei EulerOS (expired in September 2022)

https://en.wikipedia.org/wiki/Inspur_K-UX

https://en.wikipedia.org/wiki/EulerOS

These were both based on Red Hat.

And famously, GNU's Not UNIX

Huawei managed to get their RHEL fork (EulerOS) UNIX certified. However their certificate expired (probably due to sanctions?)

So legally at one point a Linux was Unix.