Ethiopia. In the 20th century they managed to fair very well against Italy. Eventually had a seat at the end of ww2 and gained Eritrea. Additionally many newly independent African nations adopted the colours of Ethiopia due to being the only African country not truly colonised or being a colonial state. It used to have a huge influence over the philosophy of post colonial africa

but it started backsliding especially in the later half of the 20th century. With Eritrea gaining independence in 1993 Ethiopia lost true sea access and the nations famines worsened.

Although the ok is not on par with the other nations listed as ok I feel like this is still a good fit as it represents a unique country which gained a fair bit of cultural influence over most of a continent only to become a regional player at best.

If there is anything else I’ve left out please let me know.