If creating a new program is too expensive then nationalize existing insurance companies and convert them into state charity agencies providing free health care.
How would that work? Insurance companies arent the ones who own the hospitals, they just have contracts with provider networks to provide X customers at Y reimbursement. Nationalizing insurance companies would just get you lists of customers and providers, its not like the feds can unilaterally void millions of contracts, and expect the parties to just shrug and fully perform as though you didnt just rob them blind. Plus the feds would need to amend the constitution to get away with stealing that much property without due process.
I was somewhat distracted when I wrote that.