SCOTUS just upheld that the leftist states, cities, etc. can declare themselves as "Sanctuarys" for illegal immigration and that the Fed cannot withhold federal funding in order for them to cooperate/enforce federal laws against illegal entry into the USA.
While this "sanctuary process" violates the federal reponsiblity under Article 4, Section 4 and Article I, Section 8, it sets precedence that the states, municiplaities can also establish themselves as "Sanctuarys" for other over-reaching federal edicts that violates states rights as per the 10th Amendment.
Since the 10th Amendment..."The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people", clearly gives the states the authority to reinforce the Federal Second Amendment; while tiering state constitutions to it, and in some aspects expand upon it.
Since the USA is "not" a democracy" but a "constitutional federal republic" that follws democratic principals, where the states have the powers not delegated to the Federal Government. Therefore, the states have the right to manage their more local right-to-keep & bear arms rights more so than the Feds do under the Comerce Clause (Article 1, Section 8, Clause 3 of the U.S. Constitution), which gives Congress the power “to regulate commerce with foreign nations, and among the several states,... That's why past Federal laws (AWB) could not absolutley ban firearms since it would violate the Constitution.
So, simply the States, muncipalities have every right to declare themselves as "Sanctuarys" for the Right to Keep and Bear Arms under both their state constitutions, and in reference to the Second Amendment.
Proposed ligislation is clearly un-Constitutional under several Amendments. But the powers proposing this either don't believe in the Constitution, are inept and ignorant of it, or complicent in tearing this country down, or all of the above.