Medicare For All comes immediately to mind as a broadly popular policy.
For starters, because this isn't actually true.
The latest findings, from Gallup’s annual Health and Healthcare poll conducted Nov. 9-Dec. 2, 2022, show 57% think the government should be responsible to ensure coverage for all Americans, while 40% say it should not.
Currently, 53% of U.S. adults prefer a private system, while 43% support a government-run system.
Leftists often drastically overestimate how popular significant healthcare reforms actually are. The government merely offering a public option is more popular, and if I recall, was something Biden actually supported, though it wasn't ever going to the last Congress, let alone this one. Full-scale socialization of the medical system à la the British NHS is far less popular.
Edit: downvoting me for reporting
data does not change the truth, but if anyone has an actual point to make I'd be more than happy to hear it.