How will the US version of the Google Pixel perform in Germany?
As far as I know EU carriers use Band 20 and Band 3/7 in conjunction, one to cover the densely populated areas and another to cover the rural places. This Wikipedia page mostly supports my knowledge. Since the US variant has 3+7+20, it should work alright.

P.S. Are you buying from US to avoid the huge price bump in buying the global variant outright?