Congrats, Dalia! I understand why chose Google over us -- the chance to travel is hard to pass on -- but maybe we'll get you next year ;)
They can come to the USA for an internship quite easily on a J-1 visa, but they won't be able to stay easily once you want to hire them full-time.
Have you considered remote work or opening an office in Europe? Feel free to contact us at www.manara.tech/hire-engineers and we can set up a call.
Note, I don't want to discourage anyone, I hope Dalia and people in the similar situation have a great career in front of here. I'm curios about the outside perspective and why you've indicated Poland as a potential destination to relocate to the EU.