The OP, while not worded beautifully, isn’t wildly off the mark. There have been a series of Supreme Court decisions around these subjects since the Constitution started operating. Marbury v Madison (1803) basically answered the question—that SCOTUS can ultimately decide whether a law is constitutional or not; Congress passing a law doesn’t make it constitutional.
Another one that strikes me as relevant to this discussion is Martin v Hunter’s Lessee (1816) which upheld the constitutionality of a federal statute that granted SCOTUS jurisdiction to hear appeals over federal issues from state supreme courts. VA said the Judiciary Act section that granted SCOTUS that power was unconstitutional in response to SCOTUS reversing a VA high court decision.
Anti-commandeering Doctrine has been around for a while as I understand it but most succinctly codified later— NY v US (1992) and Printz v US (1997) affirmed that the federal government (Congress and the President) can neither force state governments to pass laws administering federal policy, nor force state executive officials/employees (bureaucrats, law enforcement, etc) to enforce federal law. (States and their officials are required to follow federal court rulings. State judges are compelled to follow substantive, if not always procedural, federal law.)
As I understand it (not a lawyer), state cannabis laws aren’t nullifying federal law, they’re just a refusal to execute federal policy by the states. The feds are welcome to bust up a dispensary, but for political reasons the federal government generally chooses not to prioritize that kind of enforcement of federal law.
It would be a different matter if a state interferes with federal enforcement—if the governor sent the state police to keep the DEA from raiding a dispensary, that would be nullification. Or if a state passed a statute purporting to overturn a federal judge’s decision on a federal law issue—though I guess they could do that symbolically, but the state statute wouldn't be legally unenforceable because states can’t nullify federal law.
If the question is more about having Congress pass a resolution saying that a past statute it passed was unconstitutional, but the President disagree and say it’s constitutional, then effectively the President wins because he can enforce it anyway.
If Congress said a statute was unconstitutional, and the President agreed, they could just pass a statute repealing or replacing the original one.
Though in the former scenario, Congress could remove the President (or a judge) from office in response—in that sense, Congress could “declare” a statute or action “unconstitutional” so long as Congress has the political will to enforce its view on the other branches.
This is sort of similar to if SCOTUS says something is unconstitutional, but the President ignores SCOTUS and isn’t removed from office by Congress, then is the thing unconstitutional? Maybe on paper if you choose to believe it but not in practice. Power resides where people think it does.
I don’t really see how you have much greater debate than what we already had, short of just a series of constitutional fights and crises where, at the end of the day, I see the President enforcing his view of the Constitution mostly because he has the guns, or else states violently seceding.