There are three branches. Just three. If you are a federal employee, you either work for congress, the courts, or the president. A2S1 invests the president with all executive power. All of it. It doesn’t carve out exceptions for the SEC or the Federal Reserve or USAID.
If you’ve put yourself in a place where this arrangement is literally fascism, prepare to be disappointed by the courts.
Pretty hard to square this perspective with the recent Raimondo decision, no?
Is the EPA, at the direction of the sitting president, making rules about coal power plants not an example of the use of "all executive power. All of it."? Or does A2S1 carve out exceptions for the EPA, even if it doesn't for those other agencies?
Whatever you think about Chevron deference or the specific EPA case I'm alluding to, the point is: The balance of power between the executive and legislative branches is nowhere near as clear cut as your comment suggests. Congress frequently legislates the structure and responsibilities of executive agencies. Presidential administrators cannot legally change those responsibilities unilaterally.
It's a bit more murky and nuanced than that, though.
What is executive power? Well, it's what the constitution says it is. But a lot of things in the executive branch aren't spelled out in the constitution. A more strict interpretation of it (one that SCOTUS seems to be moving toward, at least when it's convenient to achieve conservative policy goals) is that Congress should not be delegating so much rulemaking power to the executive branch.
So let's say you're the SEC. You're an executive branch agency, but you essentially write laws. You get to write those laws because Congress delegated that power in some reasonably specific ways unique to your agency. So who do you really report to? Nominally, day to day, seems like the president. But you only exist because of an act of Congress. Congress can dissolve you tomorrow if it wants to. Congress can also give you more power and more latitude (within some limits, of course). So while you report to the president, you're accountable to Congress. That might mean that the president isn't allowed to fire your people without cause, if Congress specified so.
That's not an interference of executive power if the power you wield actually flows from the legislative branch.
You are not a great fan of Morrison v. Olson, are you?
However you read the constitution it's not the way courts interpret constitution now. Unitary executive branch doesn't exist for last ~135 years, and was under scrutiny before that (and with way smaller federal government).
With current supreme court nothing is sacred for sure, but overturning this and granting universal executive power into hands of president would be a disaster leading towards either authocracy or revolution. And yeah - that's all very similar to how fascism started, whether you would like to see it or not.