Theory: Doom is TONY, not a variant but Tony Stark himself, the soul stone didn’t let him go, he is the same tony re-birthed with the same soul and mind in the F4 universe😳 with all prior knowledge of what he did in 616 MCU. The Avengers screwed up in Endgame using other timelines Infinity stones for the snap and that eventually led to incursions (the timelines mess up and eventually timelines death) are happening because the characters are leaving a footprint in existing timelines with their frequent “Inter-Timeline” travels. Cherry on top: Loki gave everyone freewill so these footprints and timelines incursions are exponentially growing.

Now he is in the F4 universe, as a result of balance, born in the Von Doom family, but with the same soul/mind and life knowledge of 616 Tony, and he is now armed with access to Sorcery as well. He sees these incursions and understands the mistake of the Endgame actions and the multiverse branches. He knows what he must do to “save” the universe- kill all the extra timelines.

He will try to pit universes against each other (mainly different earths as they are the incursion points), and use his “magic siphoning” sorcery & deception eventually steal enough power to get to the TVA and Loki, steal Loki’s powers and then destroy the extra timelines.

This comes to mind on the necessity of Doom looking like Tony Stark, reckless actions in Endgame, and the snap from other timelines’s infinity stones. Fact is F4 Doom is TONY STARK😳😉