> The Fed just handed out cheques to all Americans because Congress asked it to.
Uh, no, the Fed didn't.
The US Treasury did because Congress directed (not asked) it to. Congress can make non-binding requests, but neither round of stimulus checks was a product of such a nonbinding request, and neither was executed by the Fed.
> It was unprecedented in US history
The size was bigger, but broad individual stimulus checks based on past tax filings are not unprecedented in US history. They were done in 2001, for instance.
> Under what circumstances would that be possible with Bitcoin?
Fiscal stimulus would be just as possible with a Bitcoin monetary system as a fiat one; the difference is that the divide between fiscal and monetary policy, which MMT correctly points out is artificial in a fiat system, would be a hard divide in a Bitcoin system, which would mean that where in fiat securing financing such as by selling debt is not strictly required for deficit spending, though traditionally done because of the strength of the belief in the fiscal metaphor, in a Bitcoin system there would be hard constraints which would require financing of deficit spending. This would probably drive up the cost of borrowing, since while lenders don't want borrowers to monetize debt, the fact that they ultimately can reduces default risk since it is impossible for a debtor whose debts are denominated in its own fiat to be forced to default through insolvency.