In Poland, business incubators for freelancers exist and work; you can obtain a residence permit on the basis of work in them.
I recommend the MojaFirma incubator, I’ve never been let down in five years, I still work with them.
But do not mess with TwojStartUp, I lost both money and time. This is due to incompetent staff, up to senior management, who do not care about you.
The rest of the incubators are more focused on the domestic market, on the Poles and their business, therefore there is less experience working with foreigners and the orientation is mostly NOT on freelance and IT. And higher payment for services.
Incubator services cost about $ 150 per month. And that’s all, no “hidden fees” (well, from what I came across). The main thing is to have time to withdraw money before the end of the month, like your salary, or they will become the "profit" of the company and have to pay another 20% of income taxes.
Through an incubator, you work under a subcontract. Taxes are about 16-18%. Honey. you arrange private insurance (about $ 35), that is, you do not pay% of salary for "state" honey. insurance. You can not pay the pension fund either, the agreement allows, but then it is clear that there will be no pension (although private funds can be found, no problem).