This is an interesting hard question, since support for M4A is THE signifier for the american left, and this is mostly a settled question in europe. Sure, a singlepayer system is on the agenda for some left parties where there is a partly public partly private insurance market (e.g. germany) and the left would prefer a singlepayer system when building one from scratch. The issue is not that high on any agenda (pay for healthcare workers is a much more important topic there). But the fight for a healthcare system seems much more desperate (people dying because insulin is expensive) and energetic in the us, and I think therefore many europeans see the american left as much more radical than they actually are.

From a policy standpoint AOC would perfectly fit in with Angela Merkels CDU (christian conservative) , though from her age cohort and mannerisms (also: more online, woc) she could as well be in the right wing of the german greens (which are basically gentrified and woke conservatives). In france I would solidly place her in Macrons thoroughly neoliberal en marche.