The Russo Brothers, directors of Avengers: Endgame recently confirmed that both Howard the Duck and Nova were present at the final battle with Thanos.
If you recall, Doctor Strange and his fellow masters of the mystic arts brought everyone from different parts of the galaxies to battle Thanos’ army at the end of the highest-grossing movie of all time.
I checked the fight frame by frame and saw Howard the Duck. As for Nova, I saw two people that may have looked like him and I am not sure if he was who I saw. Also, Marvel Studios made a huge mistake during the post-production of the movie and during the final fight, when Ant-Man was busily hot-wiring the quantum tunnel as Black Panther was charging through Thanos’ army with the infinity gauntlet, Ant-Man was shown as Giant-Man in the background.
Check out the proof that Nova and Howard the Duck was in Avengers: Endgame, as well as the giant mistake Marvel made in the video below.