The healthcare sector is already 20% of GDP in the US. A significant chunk of the value it produces is pocketed by the owners of pharma, insurance, and hospitals, and administrative bloat, while understaffing and even layoffs of nurses is commonplace. Doctors are extremely skittish to the point that they buy malpractice insurance in case a patient sues them (and they very well might need to just so they can afford the steep cost of future care needed as a consquence of malpractice), and often only accept certain insurance carriers known as preferred providers. Training up medical professionals is also absurdly expensive because of the long time investment (which is unavoidable) and the meteoric rise in the costs of education, which is the result of university owners seeking an additional source of profit.

We have the funding, it's just being fucking wasted on surplus value extraction by some of the worst rent-seekers in America. Not only would we need to invest in improving healthcare infrastructure but we would have to cut out all the leeches and redundant middlemen from the process, including the ones profiting from the higher education bubble. Nationalizing healthcare means abolishing private health insurance and replacing it with single-payer government insurance, nationalizing all the pharma companies and pharmacies, re-examining malpractice liability law, abolishing and cancelling student debt (which would include medical students), and making all postsecondary (including graduate) education government/tax-funded and free at the point of access for all students to lower the cost to society of educating and training medical professionals. Plus some other additional measures I haven't even thought of. This is a clusterfuck of a problem that could easily cripple a smaller nation-state than the US for generations.