Deciphering the Supremacy Clause
Article VI, Clause 2:
This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.
Defense of Marriage Act was "Federal Law" but unconstitutional, so States ignored it, lawfully and now "gay marriage" is practiced across the nation.
Scheduling (1) of cannabis is Federal "Law", but States are widely ignoring that and are devriminalizing, legalizing, and regulating it in contravention of Federal Law. Perhaps FDA "Scheduling" isn't Constitutional or within the realm of the Federal Gov't?
Those are two examples of "Federal Law," not being the "Supreme Law of the Land," at least not in practice.
Does the Federal Pandemic Declaration meet the prerequisites of Supremacy if a State or locality, which is NOT experiencing pandemic levels of "outbreak", doesn't acknowledge the pandemic by not producing their own concomitant "Declaration". In simpler words, if your county/State doesn't draft and publish a Pandemic Declaration, then is there a pandemic in your locality?