I had thought that tariff revenue goes directly to the executive branch for the president to spend without congressional oversight, but actually this is not correct.

In reality, all federal revenue - whether from income taxes, tariffs, or any other source - flows into the U.S. Treasury and becomes part of the general fund. Tariff money doesn't create a separate pool of funds that the president can spend at will. Just like with tax revenue, any spending of tariff proceeds requires congressional appropriation through the normal budget process. The executive branch cannot spend money that Congress hasn't specifically authorized, regardless of the revenue source.