> He has the power to cut funding for whatever specific agency he doesn’t like?
Not just that. The President is the ultimate boss of all federal executive functions. He is the boss of all the department heads. If he wants X to be done he picks up the phone, calls the relevant person and tells them to do it. If he wants Y to be not done he picks the phone up and tells them not to do it.
It is like as if at work your job is to respond to bug tickets for system A and B. And one day your boss walks up to you and says “System B is no longer important. Stop fixing bugs on system B.” He doesn’t have to then “cut your budget” or anything. He just told you what to do, what not to do, and you are expected to follow the instructions. If you don’t you will be fired.
> What am I missing here
The backstop to the Executive branch not doing their job is that the Legislative branch can investigate them, and ultimately impeach the President.
Up until now the Legislative branch was happy enough with how things were going that there were no chance of that happening. Recently the composition of the Legislative branch changed. This means that they are expected to start carring about certain irregularities the previous bunch turned a blind eye towards to.
> This still isn’t quite de-Americanized enough for me to track.
I don’t know man. You are asking how the USA government works, or doesn’t work. Ultimately if you want to understand a thing you need to understand the thing. You can’t have a de-thingified explanation, because the thing is the core of your question.