Yes the phrase undue burden is nowhere in the commerce clause itself but is often in rulings regarding it and is often used in a commerce clause context, separate from it’s use in roe v wade related case law. https://www.law.cornell.edu/constitution-conan/article-1/section-8/clause-3/facially-neutral-laws-and-dormant-commerce-clause

The fda ultimately derived it’s authority from and was able to be created by the federal government because of the commerce clause, so it is related to this. Congress granted power to an authority that decides what medicines are or are not available and has kept this uniform between all states. Sounds like at this point it may come down to a supremacy clause question and the original wording of the law that created the fda. If it weren’t for the commerce clause the fda couldn’t even really exist in its current form. The judge in the case acknowledged this but decided to override supremacy clause concerns on the basis that historically he felt states should be able to regulate anything concerning medicine or healthcare providers. It seems to me though this is an area that’s been a very defined federally controlled system for interstate commerce reasonings for nearly a century now, prior to now you don’t see states trying to outright ban certain medications, at least not successfully. Once a medication was approved by the fda for a use it was always available in the whole country for that use. If it was generally understood that it was just like fireworks or some other random product I would have expected a states to have banned drugs at least once before. There’s other examples of products like this where federal government retains control for interstate commerce reasons, like California required a specific federal law giving them an exception before they could have their own regulations for cars sold on the basis of emissions. You do see certain medical procedures being banned, like conversion therapy, or uses of medicines that don’t have an fda label, like puberty blockers being banned for helping transgender children. But I’m not aware of examples of a state disallowing an explicit fda approval. If you have examples though I’d be curious. Ultimately I don’t feel really qualified to go any further on this, but I did find this write up helpful for anyone interested in more, and much better informed and written up than anything I could do. https://academic.oup.com/jlb/article/10/1/lsad005/7078178?login=false

I can say though if this is allowed to stand, I would expect even worsening interference by state governments into your doctor’s office and what they are allowed to prescribe or treat you with. I’d also expect continuing worsening of medical access and continuing flight of doctors and other health care providers to states that actually allow the free practice of medicine and use of fda approved medications.