It must at least involve Congress!
What's happening here is crazy: It's the same as if Congress authorized $X for a city bridge and Trump comes in and holds up the funds demanding a cut/kickback of the tolls.
The Constitution does not give the Executive the power to arbitrarily modify what Congress has authorized, converting between grants versus loans versus stock-purchases versus plain extortion.
That they were grants instead of any other instrument appears to be a Biden Commerce decision, not a congressional one.
I’m no lawyer and could certainly be missing something i the law that says it has to be grants but from what I see it looks like figuring out what to do the the money was pretty much delegated to dept of commerce with limited direction about eligibility and review criteria.