I’m not sure moving committees, such as that one, to anther branch of government would achieve much. In the end, these committees are intended to allow the legislature to make better decisions - moving their functions away from the legislature doesn’t help.

Then again, the US system of government is not exactly a model for the 21st century.

Investigations and information sharing would be principle functions of this branch. I do not see the problem. They'll publish findings, and legislature may then deliberate on these findings to alter laws or enact new laws. If the operational branch discovers violations, it can then forward their findings

Decoupling the leadership of the oversight of the executive from the dominant party in the legislative would be benefitial. This is already possible in context of executive and judiciary. As it is now, these committees are subject to partisan games.

Further, the legislative permits lobbying whereas there is no room for lobbyist pressure on this body. None.

> the US system of government is not exactly a model for the 21st century.

I am drawing a blank imagining which existing system today would fit that bill.

Additionally, there’s no reason why government auditors have to do things annually like auditors for companies do - government auditors could quite easily audit smaller parts of the government at shorter or longer intervals.