> You probably need to be 18 to sign up, but no Polish person ever actually cared about such restrictions and there's no age check.

You need to be 13.

>On the other hand, cloud services require you to have a debit or credit card, which you can't get without an intervention from your parents if at all.

With parental permission, a 13-year-old can open a free bank account with a debit card that works online. It's not a new thing, I had one 15 years ago.