The fields of biology, genetic engineering, and (unfortunely ITTL still considered a valid science) eugenics may be more advanced than in OTL, given that the *USA has no qualms on carrying out various forms of dubiously ethical medical research on low-ranking peons with basically no rights.
I doubt this, largely because it's
often overstated just how much useful data actually came out of the human experiments carried out by Nazi Germany and Imperial Japan. The short answer is: not much. Sigmund Rascher's experiments on the limits of human endurance, conducted on hundreds of unwilling prisoners at Dachau and Ravensbruck, have been widely cited in medical journals since, but that's about it. Most of the rest was just creative ways to torture people to death, the resulting data more or less stating the obvious, like that you can't survive on salt water alone for two weeks or that injecting dye into your eyes will blind you. Even when they did produce useful data, the West was making the same, and arguably better, progress under more humane conditions. You can also look to the Tuskegee study, the results of which were more or less "syphilis will fuck you up", which was common knowledge for decades by that point. And of course, OTL's eugenics movement produced virtually nothing of value to science or medicine, and was already falling into decline in the 1930s even before WWII fully discredited it.
That said, even though the *US probably won't make any serious advances in medical science that the rest of the world isn't beating them to, they
will probably find ways to use it as a tool of social control, and come up with a lot of splendid little crimes against humanity in the process. Once mechanization takes over agriculture and makes a lot of farm laborers redundant, expect to see a widespread sterilization program to cull the slave and peon populations. They'll try to come up with an ethnic bioweapon for much the same purpose, only to cancel it and bury all the evidence once it accidentally backfires on the white citizen population. To deal with the possibility of revolt, expect to see an alt-MKUltra, on steroids and done more or less openly, that won't necessarily produce a
docile underclass like they hoped but
will leave a whole lot of people driven too insane by drugs and medical torture to even consider organizing a rebellion -- so, in a sense, it could be seen as a "success" for white *America. Expect to see an attempt at a super soldier program, one whose only legacy will be a lot of broken veterans suffering from a lifetime of physical ailments. And just like how the Nazis discredited eugenics in OTL, expect the *Americans to do the same ITTL once their worst abuses are leaked to the outside world, just like how they discredited overt racial supremacy outside their borders (in favor of the sort of cultural supremacy embraced by the Germans).
And of course, there's likely to be a lot of pulp literature and exploitation films about *American human experiments. Medical horror could well be a staple of the New England film industry, given that country's proximity and cultural antipathy to the *US meaning that stories of their abuses will circulate far and wide, likely with government support.