My very not-legal-advice, probably missing details summary is that the way the Farm Bill was originally written was to outlaw hemp-derived Delta-9 THC over 0.3% by weight. So long as the total amount of D9 THC derived from otherwise legal hemp in anything is less than 0.3% by total weight of the product, it's legal. In order to stay under that limit, all you need to do is make sure your 5mg gummy weighs more than ~167mg or so, which isn't difficult.
Joining the “IANAL” and “YMMV”: The big catch here is that at no point in the production process can it have over 0.3% by weight, so you can’t just add a concentrate to the item if the concentrate is over 0.3%.
There's a whole thing about whats THC and what counts as processing. DEA went to the courts to try to get all THC lumped equally. Courts replied that thca and Delta 9 are not the same thing and that the farm bill means what it says when it limits Delta 9 in products and limits total THC 30 days prior to processing. Then there's the question of whether processing means harvesting or whether processing means growing and when that limit actually applies. Rod Kight is a cannabis lawyer that has some articles on it.
https://cannabusiness.law/about/rod-kight-international-hemp-cannabis-business-law-attorney/
That is legal - the one good thing your racist asshole Grandpa (unknowingly) did while in office. Flower too. Try flowgardens.com or eighthorseshemp.com or a bunch of others.
Like the other person said, the law limits hemp-derived THC content to a percentage by weight, so soda/beer and gummies can have a lot more THC in them since they weigh a lot more than dried plant matter.
I actually won't know until my next trip. Decided to bring a tincture with me for the trip and didn't try the infused. Highly recommend visiting WI especially the supper clubs and the track at Road America.