In this piece[0] "Пушкин - Юрьеву"

He refers to himself as "a disfigured descendant of negroes".

"А я, повеса вечно праздный,

Потомок негров безобразный,

Взращённый в дикой простоте…"

Also, here's an interesting article about Pushkin with some African Americans claiming him to be one of their own, with examples from 1929 and 1983:

https://www.livelib.ru/articles/post/63022-kak-pushkin-stal-...

[0] https://ilibrary.ru/text/182/p.1/index.html

EDIT: There's also this article exploring his African heritage:

https://daily.jstor.org/how-alexander-pushkin-was-inspired-b...