I'm not making it up out of nowhere!
> Meaning "office of a professor" (1816) is extended from the seat from which a professor lectures (mid-15c.).
https://www.etymonline.com/word/chair
Seems to be in-use in the US?
https://depts.washington.edu/givemed/prof-chair/creating-you...
It even talks about how the endowment for the professorship or chair funds the professor.