Hidden certifications ?

Hi,

I read about the PSP certification, which is not mentioned on the https://www.scrum.org/Assessments.aspx page, but present on the https://www.scrum.org/Assessments/Scrumorg-Certifications page.
I wonder how to access the PSP page, because I would like to mentor my co-worker beyond the PSM I.

I also wonder why the https://www.scrum.org/Assessments/Scrumorg-Certifications didn't mentioned the PSE and PST holders.

Yours
Olivier