I don't think that's really possible. The issue isn't so much that there isn't proof, it's that proof existing would be counter to everything we know about how the universe works. It wouldn't just mean "oops I'm wrong" it would mean that humanity's perception of reality would have to be fundamentally flawed.

I'm not even opposed to believing that our perception is flawed - clearly we don't know everything and there is much about reality we can't perceive let alone understand. But this would be so far outside of what we do understand that I cannot simply assume that it's true - I would need to see it to believe it.

There are virtually limitless ways such a being could make itself evident to humanity yet the only "evidence" anyone can come up with is either ancient stories or phenomena more plausibly explained by other causes. To me this completely tracks with the implausibility of the existence of god.