Why Are There No Avengers At T'Challa's Funeral?
In Black Panther: Wakanda Forever, none of the Avengers attended T'Challa's funeral despite their personal friendship with him. As Black Panther, T'Challa joined the Avengers and made his MCU debut in Captain America: Civil War. In Avengers: Infinity war, T'Challa welcomed Earth's Mightiest Heroes into Wakanda and even put his realm in danger to give safety to Vision. Because of his charismatic leadership, Black Panther was the first hero to emerge from the portals in Avengers: Endgame, leading Wakanda's army in the conflict with Thanos.
But not a single Avenger was there for T'Challa's funeral. Given their availability and respect for the Wakandan king, one would anticipate Bucky Barnes, sam Wilson, Smart Hulk, war Machine, or Hawkeye to attend. To maintain the funeral's cultural significance, it's likely that T'Challa's family kept it a Wakanda-only event. Perhaps no one outside of Wakanda learned of the funeral until after it was done. After all, before he was a superhero, T'Challa was a king to his people.
In Black Panther: Wakanda Forever, very few Avengers would have been able to attend T'Challa's burial. By this time, characters like Thor, Valkyrie, Ant-Man, doctor Strange, and the Scarlet Witch, for instance, are probably immersed in their own MCU Phase 4 adventures, whereas Spider-Man is away putting his personal life back together and Captain Marvel and the Guardians of the Galaxy are away from Earth. The Avengers' heroes who could have represented them at T'Challa's burial, iron Man, Steve Rogers, and Black Widow, are now deceased, while Vision, who could have returned Black Panther's favour from Avengers: Infinity war, appears to be regaining his memories within White Vision's body.
Despite their busy schedules, Bucky Barnes, sam Wilson, Smart Hulk, war Machine, and Hawkeye might have made time to assist T'Challa's family during his funeral. They must be concerned about other things as they most likely weren't invited, which is reinforced by Everett Ross's absence as well. sam Wilson's initial missions as Captain America must be assisted by Bucky Barnes as he continues to seek inner peace. Depending on where Black Panther: Wakanda Forever is in the storyline, Smart Hulk might be working in his lab or meeting his son Skaar on Sakaar. Clint Barton is probably taking advantage of his retirement while preparing Kate Bishop to be the next Hawkeye, while james Rhodes must be preoccupied with his obligations with the government.