The ending of Black Panther: Wakanda Forever is about grief, not conquest: Shuri spares Namor after seeing her mother's vision, and Wakanda and Talokan end their war with an alliance. In my opinion, that is the boldest choice in the film, because a superhero finale would normally end with the villain defeated for good.
The key beat is Killmonger's question on the Ancestral Plane, whether she will choose revenge or follow T'Challa's example. Michael B. Jordan returning as Killmonger from black panther 2018 is a deliberate echo, because that film also made its antagonist the voice of the hero's conscience. This time the question is put to Shuri, and the fight on the desert beach is her answer. She has Namor beaten, and she chooses mercy after the vision of Ramonda, who drowned saving Riri.
The closing scenes tie off the loose ends. Shuri secures the future of the Black Panther role by planting more herbs, and M'Baku challenges for the throne in her absence. That is a neat reversal of the first film, where M'Baku challenged T'Challa in ritual combat at the coronation and lost. Okoye rescues Ross, and Riri goes back to MIT. Finally, Shuri visits Nakia in Haiti and burns her funeral robe, letting herself grieve T'Challa at last.
The production history explains why the finale is so quiet. According to the AP, Ryan Coogler and Joe Robert Cole rewrote the script after Chadwick Boseman died in August 2020, moving the story from T'Challa to Wakanda's grief. Photos of Boseman were posted on set, and a shield and spear from his duel with Killmonger were placed in Coogler's trailer, so the burning of the robe reads as the film's real farewell rather than a battle result.
Compare it with thor love and thunder, released a few months earlier, where the villain Gorr is also driven by the loss of a child. Both films build their antagonists around grief, but Wakanda Forever lets its hero end the war through restraint. Perhaps that is why it feels so different from the Infinity Saga finales such as avengers endgame, which closed on a decisive victory.
It could be argued that the film leaves Wakanda with a new Black Panther and a changed relationship with Talokan, a different footing for the saga ahead of avengers doomsday.