If you are a expat and want to create a startup in Berlin, how hard is it? what would you need? how hard is to get the visa? I've seen that France was creating

If you are a expat and want to create a startup in Berlin, how hard is it? what would you need? how hard is to get the visa? I've seen that France was creating a "startup visa" to help foreigners founders to create companies there. Is there something similar going on on Germany? Im realling looking over this, and was thinking about Berlin, Paris or Rio (on my own country) Edit: I also can go for the Polish citizenship as a polish descendant and get into the EU that way as another option