You're thinking of this way too formally. The president has wide latitude to restructure his cabinet staff underneath the handful of secretaries that congress has to approve, and appoints--without needing congressional approval--thousands of people within days of getting into offices for all sorts of leadership positions in the government's agencies, who can then restructure beneath themselves again without congressional involvement. For example one way to get a de facto DOGE might be to put the people you want forming it into all those leadership positions and then have those who would normally be considered the leader hired as "under" them as the vice leader instead. Any set of rules can be gamed. You just have to be creative determined and resourceful enough.

Ultimately the government only has to follow its own rules to the extent that the people appointed in the executive branch agree on an interpretation of what the rules are. Congress nominally makes the wording of the rules, but since the executive branch carries them out, they get to interpret as hard as they want to. At most the courts might tell them months or years later that their interpretation was wrong and they have to stop. But there again it's the executive branch carrying out the will of the court, and determining what any "new" interpretation will be until they get dragged through court again.

The whole circularity of the logic of restraint is how they've been able to accomplish all sorts of unconstitutional and beyond-their-remit things that have happened in the last few decades. It's how they effected the lockdowns during the 'rona. It's how the ATF has recently attempted to completely change the "rule" that defines what a pistol brace is and retroactively make millions of sold products illegal without a tax stamp--all without any congressional legislation whatsoever. It's how Trump banned bump-stocks last time he was in office (though that one's been at least partly reversed).

Congress, and to a lesser extent the courts, have voluntarily delegated more and more of their powers to the executive branch over the last 100 years or so. I don't claim to know which tricks they will use to interpret the law in order to give DOGE power---nor if he will even follow through on the idea. But there's no reason to doubt that Trump can do a lot more than nothing if he really wants to.

And finally let's not pretend that it's impossible to get Congress to approve a new agency or increase funding if Republicans decide that sounds like a popular thing to do. If the politicians in congress do it "right," they could even subvert DOGE into just another layer of bureaucratic power for them to wield instead of being the paring-down force that Trump, Elon and friends have been saying it will be. We'll see what everyone does, but there's no reason to say they won't do anything.

If that were the case the Democrats would have given the Sierra Club the authority to deny development and construction projects themselves rather than having to petition TRUE government agencies like the EPA.

Both parties actually do put their friends into the EPA and other agencies when they're in power through the appointment powers of the presidency. But it doesn't get reported and it's specific individual cronies rather than the entire Sierra Club, whose agenda as an organization isn't in line with the real agenda of Democrats anyway. The fact that the EPA and other agency's behaviors don't usually swing wildly between administrations is more to do with how similar the two major parties really are in their inner thoughts, and how slow it is to change huge organizations from the top