A possible scenario, with or without Indy, that involves the Ark arriving in Berlin, might have ended up with Hitler choosing to do with it the same as the US Government: put it somewhere safe (assuming that Belloq had already proved its lethality).
The Ark is an indiscriminate weapon of mass destruction. It will kill anyone who sees the ghosts. So it’s not much use unless it could be handled by a specially trained group of blind operators, and protected by people with blindfolds.
The enemy would then train their own blind commandos to combat the Ark and the whole thing would be a right old mess!
For the Americans it was obviously safer to drop two atom bombs on Japan than strap the Ark to the belly of the Enola Gay and use the pilots as ghost-fodder, losing the Ark in the process.
It’s also a potential doomsday device, since who could be sure the ghosts would always return to their box after a killing spree?
In 1945, Hitler would very probably have ordered the Ark to be opened in Berlin, thus killing everyone he deemed no longer worthy of living as part of his scorched earth decision, which Speer would have refused to carry out.
In 1949 the Ark would have been banned by the Geneva Convention, solving all of the above issues!