If it is shown to be doable literally every major nation state (basically the top 10 by GDP) is going to have it in a year or two. Same with nuclear fusion. Secrecy doesn’t matter. Nor can you really maintain it indefinitely for something where thousands of people are involved.

In addition, it's also a big assumption that money will continue to matter or hold its value in such a world.

Anyone who solves AGI will be the government.