GPA is not any more/less important than here but depending on where you want to go, they will probably have special requirements for foreign students. I was looking at Oxford's requirements yesterday, for example:

International qualifications | University of Oxford

and I imagine all the schools/countries/universities have some sort of page like that you can find? The biggest problem I found is their whole way of approaching schooling is different from ours; in England, for example, college is only 3 years and you only study your major subject, not all the other stuff like we do here in the States.

I would enroll in a good European History program here in the States and then transfer after a year or two of getting all the math, science, English, social science, etc. in that we require but which the Europeans usually learn in what would be a 5th year of high school/junior college to us. You have to know all that stuff before their advanced schooling usually and pass a test, etc.

I notice the Sorbonne has partner schools in the US, you could also see how to enter a program here, and then transfer there?

Aux Etats-Unis | Sorbonne Universités

I have a history BA from a good program here and last year got into and took a year-long history degree program from Oxford that is roughly equivalent to the 3rd year of their colleges (in other words, having done well I could, if I lived in England, get into graduate school there). It was hard to get into, even with my 4.0 history major gpa. I had to write a paper based on readings I downloaded and know of an English woman, former school teacher of Literature who did not get in because they told her she could not write well enough (she had to be able to write "history" and she obviously could only write English literature). Even having gotten a 4.0 in history courses here and a BA, I will only graduate with the equivalent of a "B" or "B-" (their grading is foreign to us too). Taking European history in Europe, you would already have to know a whole lot more than we possibly could, having been raised here. It's the whole culture and how we were raised, etc. that makes it much harder.