I'm not a tax consultant myself but in case a government audits your company or the freelancer and finds you guilty of this, the money owed is not a small sum I would imagine. It seems the situation in Germany is that your tax and social security scheme is determined by your living residence. So if you work and live in Germany but work for for a US firm remotely you are bound to the German tax code and entitled to social security services as is anyone else in the country. I would be surprised if France or the Nordics would be less restrictive on this. And it makes sense from a legal intuition standpoint.
Best is probably to consult with other startups which employ folks remotely and check in with an expert.
[0]: https://en.wikipedia.org/wiki/Misclassification_of_employees...
Working "for" the usa company remotely, is I believe, still quite different to "selling services to a foreign us company while self-employed under your own company".
Right now for instance, I have a regular job, plus tominini which allows me to do additional work for whomever I like, with the onus on me to pay taxes / benefits etc.
So yeah, Europe to me seems to take a generally very negative view of the "Uber/food delivery"-style of potentially abusive employee relationships, and you'd have to be careful about that, but I don't think it's an insurmountable hurdle.
I guess narrow down the country and role description and it might get clearer, and contact some other startups like thenaturalist suggests.
That said, saying 'we want to hire someone in Europe', is ... rather vague, you realize? What do you want them for? Sales, tech? To start a foreign branch? You'll probably have to narrow your purpose down (to get decent advice, or for your own benefit as well?)
Good luck