Not an American but there’s only very limited circumstances you can travel across the border home to the USA with foreign prescription drugs, right? And this scenario wouldn’t cover it. Unless you just meant they won’t get caught or maybe not fined or confiscated in practice? :)
That's mainly for visitors. If you're a US resident, you can't just buy medicines abroad, unless of course we are talking about the "they won’t get caught" scenario.
US residents can buy medicines abroad the FDA link says personal importation is allowed as long as the medicines are FDA approved and are not being imported for commercial purposes. Now in the context of the original post maybe generic versions of Ozempic won't technically be FDA approved yet if the company that produces it has to wait for the US patent to expire.
Of course you can buy medicine abroad and legally bring 90 day doses.
More over, you can order and ship medicine, including ozempic and zepbound, using American prescription from Canadian online pharmacies. For some drugs it’s quite cheaper than paying American prices.