I agree with you in spirit, that we're further left than the American left realizes. But on this particular, I think you're wrong.
Feel free to read it as “as broad as it is”, different polling from around the same time toward the end of when it was an active issue varied widely (I can find different polls from about the same time putting it at 30% and 11% support), and the exact breath of support isn't really relevant to my point.
Not to derail, but extending public health care to undocumented immigrants in a pandemic just makes sense. Undocumented doesn't mean vaccinated, so there's a clear public interest in minimizing the absolute number of COVID-19 carriers, no matter their legal status.