Yes, if it wasn't clear "state" meant our individual states, not "the state".
Congress actually has monetary powers, including:
Article 1, Section 8
The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;
To borrow Money on the credit of the United States;
To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;
To establish an uniform Rule of Naturalization, and uniform Laws on the subject of Bankruptcies throughout the United States;
To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;
And the US Mint does make coinage.
And the US Treasury Department of Engraving does print bills.
But the Fed regulates money supply through buying US Treasury securities and some other open market operations.
The shit is complex.
Point being - Fed Coin probably won't be deemed unConstitutional, especially if politicians and their business allies really want it.