Very little? States abolished slavery or put themselves on the road to abolition. Jefferson wanted to blame King George for slavery and the slave trade, though the Continental Congress took those words out of the Declaration. Washington eventually did free his slaves. Hamilton's friend, John Laurens wanted emancipation in South Carolina. Abolitionist societies were formed. Slavery was banned in the Northwest Territories, and the Constitution authorized an end to the slave trade in 1808. Foreigners like Lafayette and Kościuszko did what they could to help Americans live up to their professed values and convictions.
Not in 1776 they didn't. Massachusetts started their Judicial activism after 1780, but this wasn't the same as the people voting to get rid of it.
Trying to make 1776 and the Declaration of Independence about slavery is dishonest.