The Multiverse Evidence
The MCU multiverse has provided strong evidence that another Avenger could have survived Iron Man's Endgame snap. As seen in Marvel's What If...? season 2 finale, the Infinity Stones are instrumental in preventing a major multiversal crisis. However, the one who wielded them survives with no consequences compared to Bruce Banner's Hulk who was injured after using the Stones, or more importantly, Iron Man who gave his life in Avengers: Endgame.
Carter Punches Strange With Infinity Stones
In Avengers: Endgame, Earth's Mightiest Heroes successfully collect the Infinity Stones in the past to bring back those they'd lost in the present. However, they were immediately attacked by Thanos who sought to use the Stones to restart the whole of reality from the ground up. By the end of the major battle, Iron Man gave his life using the Infinity Stones to erase the Mad Titan and his forces, and it was confirmed by Doctor Strange that it was the only way the day could be saved. However, What If...?'s Captain Carter suggests another MCU hero could have wielded the Stones as well.
Captain America and Iron Man in Avengers: Endgame
Captain Carter's Feat
While fighting Strange Supreme in What If...? season 2's finale episode, Captain Peggy Carter evens the odds by wielding the Infinity Stones used by Infinite Ultron and Erik Killmonger in the previous season's finale. Integrating Killmonger's armor and the Stones into her own suit, it follows that the armor offered the same amount of protection as the standard Infinity Gauntlet or Tony Stark's nano-gauntlet. However, the intriguing part comes at the end of the showdown after Strange uses his dark magic to knock the Stones from Carter's grasp.
Thanks to Kahhori who was fighting Strange alongside Captain Carter, the Tesseract-powered warrior uses her powers to return the Stones to Peggy. Carter then grabs all the Infinity Stones in one fist before punching the corruptive demon possessing Strange in his grief over his lost world, temporarily knocking the beast out of the sorcerer. However, Peggy suffers no injuries nor critical damage despite this incredible feat with some of the most powerful weapons in the MCU multiverse. As such, it seems as though Carter must have been protected by the Super Soldier serum, even if her armor was still providing some level of protection.
The Case of Captain America
Using Captain Carter's impressive feat as the foundation for evidence, one has to wonder if Steve Rogers' Captain America could have survived the snap that killed Iron Man in Avengers: Endgame. If Peggy was able to survive with no damage, it follows that Rogers would also have been fine due to their shared status as Super Soldiers.
However, it stands to reason that Doctor Strange was still right in that Iron Man wielding the Stones was the only path to victory. After all, Tony Stark was the only one with the nano-tech that allowed him to take and wield the Stones before Thanos realized he'd taken them. As such, it was seemingly more a matter of time and circumstance as opposed to ability, despite the new evidence provided by What If...? and Captain Carter.
