What prevents us from giving this system access to other real systems that live in physical labs? I don't see much difference between parameterizing and executing a particle accelerator run and invoking some SQL against a provider. It's just JSON on the wire at some level.

Nothing, we can give it all the data we have and have it lead experiments.

But we can not yet experiment at the GR/QFT frontier.

To do so with a particle accelerator it would need to be the size of the milky way.