In Australia we have a single payer with private alongside. It is not good to have the private alongside but it is definitely a good step.

To make it happen in the USA I would hope for a government system to cover people who are currently not or poorly covered, so basically a below bronze tier plan, that is funded through a specific levy on something disconnected from healthcare, say corporate profits or very high income. Cover just the lowest of the low at first, the people who currently get nothing, and then gradually expand it, eating into the low end of the market. Every year bring more people over, eventually bringing everyone over and outlawing private.

As for how to actually manage the healthcare itself, I think it would make sense for government hospitals to be run by the government and for everyone there to be on a salary which is reasonable and provides stability. Maybe have a specific tax incentive for new doctors/nurses/other professionals to do a number of years, say 5-10, for a significant reduction in their university costs. Make sure that the entire system is aimed at long term impacts on health so dentistry should be included, perinatal, early childhood, and so on. Always be looking to prevent health issues rather than treat. Aim for quality of life enhancement as much as possible.

Once you have a base system started you can also branch out a little, adding linkages to schooling for the dietetics and exercise physiology stuff, aged care facilities for geriatric and cognitive health stuff, and so on. Make sure that alongside all of this you properly fund and support the independent operation of Native American healthcare and try as much as possible to have a system meeting people where they are with members of that community, so try to encourage underrepresented people into medicine and support their educational attainment.

As for the state by state thing, ditch it. This is not different based on which side of a line you are, it is different based on the medical needs of every person in every community. Some areas will need more support for drug and alcohol induced issues, but honestly they are needed everywhere so just make that available everywhere. Same with geriatric care, there are old people everywhere. Oklahoma does not have different humans to California, just different laws and different contexts, but making sure that each individual gets the care they need is the central rule.

Lastly, use this as an opportunity to roll out an eHealth record system. Make it national, ideally make it interoperable with Europe, and make it very secure. By secure I don’t mean ask Microsoft for help, I mean have the NSA and so on run red team ops on it, trying to get in, for the life of the system, then fix holes they find. Make sure people own their own data and can access every report and record from their portal. And also do thorough consulting on delegation of access, sometimes your partner having access to your records is a bad idea.

The first possibly doable thing, would be adding a public option to the the ACA marketplaces. I don’t know who would manage it. Medicare maybe.