I could easily see a POD right after the Civil War, either because Lincoln lived or from a Seward Administration. Lincoln believed (correctly, as it unfortunately turned out) that the only way African-Americans could retain their freedom was if they were resettled out of the United States. And Lincoln actually attempted to negotiate a massive transfer of African American freedmen to British Guiana and British Honduras (now Belize) in 1964, but the British were not interested.
Suppose the US goes to war with France in 1865 over France's establishment of Emperor Maximillian as Emperor of Mexico instead of simply massing 50,000 troops on the Mexican Border OTL. Since by this time, the US had a rather large navy, I could easily see a war with France resulting in the US taking not only Mexico (and keeping Mexico) but taking and keeping French Guiana, Guadaloupe, Martinique, French St. Martin, Tahiti, New Caledonia, forcing France out of the two Vietnams and Cambodia, creating an open door policy there---and taking the French African colonies and then settling large numbers of freedmen there. The purpose would not only be to create a home for freedmen, but as an excuse for a US protectorate in Africa with African-American freedmen as US proxies. Would this lead to independence for Liberia reasonably soon? Or would Liberia (extending to the Senegal River and to the Gold Coast with the exception of Gambia and Sierra Leone, both held by the British. And Libereville on the Gabon Coast. It would give the US some skin in the scramble for Africa Game How soon in this scenario would a Greater Liberia achieve independence?