It's an act of direct monetization that proves Congress won't pay it's obligations... fixed income markets would freak out.
We don't know how forex markets would react. I would expect them to instantly back away from current valuations in the event that the U.S. instantly monetizes.
Brokers bid on debt and then sell it, use it as collateral, etc... on secondary markets. Its all based on faith. Yellen is already on the record for saying it's a no-go.
We would be crossing the Rubicon. Given that Republicans have used the term printing money to refer to any time Democrats enact deficit spending, the term will have lost some of is political luster. There is also the risk it becomes a political issue that galvanizes the GOP much in the way that abortion did for Democrats in 2022.
My assumption (please correct me where I am misreading you) is you view the Fed purchasing a special coin as direct monetization, does that mean the Fed purchasing Bonds (or Debt held by the Fed) is indirect monetization? That would mean that some $6.89 trillion is not direct monetization. That does not jive.
The exchange of national currencies is subject to the same supply and demand forces as just about anything else, but more importantly the valuation spot to spot is based on competition. No one currency traded and valued like this operates in a bubble.
The point being that the Fed holding bonds (or other assets) against the Fed holding a special coin is rather meaningless to how a currency is valued trade to trade then day to day. The inner workings of a nations economy with respect to international trade capability tend to impact things far more than what debt a Nation has or what debt a Central Bank is holding. Volatility indicators aside for just a moment, as long as another nation wants to sell in the US or buy from the US then conversely as long as there is demand in the US to buy from another nation or sell to another nation that valuation could not care any less about the nation carrying $31.4 trillion, or the Fed holding $6.89 trillion, etc.
For the purposes of this conversation, it does not matter if the Fed ups that $6.89 trillion will a couple of Trillion dollar special coins. While that $31.4 trillion number will change what will not is demand for the currency as the US is still the #1 overall trade leader of goods and services.
My question is why is "faith" impacted as no one can seem to tell us that faith is really unchanged by US total Debt, Debt held by the Fed, Debt held by the Public, or some other designation?
By index, by trend (as in actuals) the US Dollar is valued higher today than it was 5 years ago.
If debt was a factor, or who holds that debt, or the disposition of that debt, or what is held by the Fed was a factor at all we would not see this behavior in the US Dollar valuation over time.
In fact, the only reason there is a valuation dip at all is because it is recent. As in when Republicans won the House and started threatening debt ceiling shenanigans where we fell from roughly 103 in Oct to 101 in Jan (BTW, in 2018 it was down in the 93 'ish range.)
Total Debt, and a few debt ceilings were smashed in that time... value hit to the US Dollar or demand for its use... crickets. We are doing fine.
What made the real difference? Demand, as in coming out of a global economic hit due to Covid and Russia ****ing up the energy markets... again. The US still wants to trade, and is still #1 in doing so, want for the Dollar is fine.