Correct as far as it goes.
Who and why someone can come into the US is law. BUT the procedure by which their application is processed is policy, including where they are allowed to stay while it's in process. DACA doesn't change the law. It allows them to stay in the US and work while their application is processed (endlessly delayed). And this he can do.
And Biden issued a Memorandum not an EO, not even an EA
MEMORANDUM FOR THE ATTORNEY GENERAL THE SECRETARY OF HOMELAND SECURITY
Sure he could issue one on mag limits but it wouldn't survive the court challenge, and his handlers know it and don't want the bad optics of a fail, or the way it would motivate the opposition. Otherwise he would have already done it.