Gonna try to come up with What If ideas for each movie that hasn't yet gotten a specific one. I'll do as many as I can.
Iron Man 3: What If... The Real Mandarin Attacked? Nexus Point: Mandarin attacks Killian for using his title.
Thor Dark World: What If... More Realms Converged? Nexus Point: Odin doesn't stop at Nine Realms, also conquers Ta-Lo, Sky World, etc.
Captain America Winter Soldier: What If... HYDRA Won? Nexus Point: Bucky kills Steve and Fury and Widow earlier on, leading the Helicarriers to attack more people. Not a good timeline.
Ant-Man: What If... Scott Disappeared Earlier? Nexus Point: Scott disappears for 5 years in 2015 instead, making him pop out in 2020.
Civil War: What If... The Accords Were Signed? Nexus Point: the Accords get altered to allow heroes to have more freedom than they would have, leading to all heroes agreeing with the Accords more.
Spider-Man Homecoming: What If... The Spider Bit More? Nexus Point: Peter isn't the only one bitten. Let's say it also gets MJ and Ned maybe others.
Thor Ragnarok: What If... Heimdall Intervened? Nexus Point: Heimdall decides to not just let Loki get his way, he helps Odin get better, Hela stays trapped, etc.
Infinity War: What If... Thor Went for the Head? Nexus Point: Thor kills Thanos earlier in the final fight.
Captain Marvel: What If... Maria Rambeau Became Captain Marvel? Nexus Point: Maris goes on the PEGASUS test flight instead of Carol.
Endgame: What If... All Avengers Assembled? Nexus Point: after the Snap, it's not just Avenegrs and Guardians and the ones we saw, it's also Defenders and Eternals and every super character that wasn't Snapped.
Eternals: What If... The Eternals Interfered? Nexus Point: after New York, the Eternals decide to interfere because Ajax realizes that was caused by Thanos, an Eternal with the Deviant syndrome.
Spider-Man No Way Home: What If... Venom? Nexus Point: Strange realizes there was a sixth villain that hopped universes. I think Venom being there would be neat because Peter would try to make a cure for Eddie but he'd be like nah it's fine we're cool but Peter would think he's lying etc.
Love and Thunder: What If... Zeus Helped? Nexus Point: Thor is able to convince everyone at Omnipotence City that Gorr is a threat.
Wakanda Forever: What If... T'Challa lived? Nexus Point: Shuri is able to make a cure for whatever ailment T'Challa has. I know they'd probably never make this, but I think it's worth thinking about.
GOTG 2/3: What If... Adam Emerged Earlier? Nexus Point: Adam Warlock emerges from the cocoon in 2014. He's not as fully formed though, mentally. Part of this manifests as a very alliterative speech pattern, cuz I loved that in the PS5 game.
Marvels/Secret Invasion: What If... Kree and Skrulls United? Nexus Point: Carol doesn't annihilate Hala.
Bonus 1: What If... Young Avengers? Nexus Point: the Snap kills nearly all of the adult heroes. Years later, Tony (one of the only survivors, albeit weakened) decides to find new heroes to assemble from across the world and the universe.
Bonus 2: What If... T'Challa Fought Ego? Continues from the Star-Lord T'Challa episode. Ego eventually captures Quill, forcing Fury to use every available asset in 2008. Odin also sends Thor, Loki, Sif, and the Warriors Three. Steve wakes up 3 years earlier, Fury calls Carol to help, Red Guardian joins, Hank Pym and Bill Foster join, etc.
Bonus 3: What If... Ragnarok Came to Earth? Nexus Point: Surtr doesn't get killed on Asgard, ends up attacking Earth. This is basically my prediction for one of the currently unused storyboards.
Bonus 4: What If... Mutants Were Accepted? Idk the Nexus Point, but they're clearly showing Mutants exist in the Prime Timeline, so what if they appeared in more events we're familiar with, like Wolverine joining the Avengers in New York, etc.
Bonus 5: What If... The Snap Didn't Kill? Nexus Point: instead of killing 50% of people, the Snap merges people. This is my take on Warp World in MCU.
Bonus 6: What If... Natasha Lived? Nexus Point: Natasha and Clint are on the New York Time Heist while Tony and Steve are on the 2014 Time Heist. Saw this in a fanfic, basically they have more Pym particles so Tony sacrifices his mother after getting her the night Bucky was sent to kill her. Natasha lives etc.