I think OpenAI's definition ("outperforms humans at most economically valuable work") is a reasonably concrete one, even if it's arguable that it's not 'the one true form of AGI'. That is at least the "it will completely change almost everyone's lives" point.
(It's also one that they are pretty far from. Even if LLMs displace knowledge/office work, there's still all the actual physical things that humans do which, while improving rapidly with VLMs and similar stuff, is still a large improvement in the AI and some breakthroughs in electronics and mechanical engineering away)
It's overly strong in some ways (and weak in a few), yes. Which is why I said it's not a "one true definition", but a concrete one which, if reached, would well and truly mean that it's changed the world.
(It's also one that they are pretty far from. Even if LLMs displace knowledge/office work, there's still all the actual physical things that humans do which, while improving rapidly with VLMs and similar stuff, is still a large improvement in the AI and some breakthroughs in electronics and mechanical engineering away)