Does VAT really go entirely to healthcare?

If not, we'd have to compare with the total taxloads borne by citizens of compared countries

It varies country by country and funds are essentially fungible. France for example nominally has special payroll taxes that go towards healthcare. Some OECD nations have mandatory insurance schemes where you pay some premium monthly. It really varies a lot. It is however true that VAT is pretty much universal to OECD nations with single payer systems and make up a significant chunk of government tax receipts. Its essentially impossible to dodge.

But when comparing most incomes levels, Americans pay much lower taxes than OECD counterparts.