There is no Kindle in Poland. In fact, there is no Amazon in Poland either(which is almost ironic considering that there are a couple huge Amazon warehouses in Poland - they serve customers of Amazon.de, as they are both very close to the German border - I suspect the labour costs are lower in Poland hence it makes more sense to have the warehouses there. Incidentally, going to Amazon.pl redirects you to Amazon.de instead).

However, in the absence of Amazon, domestic services have sprouted instead - there's a few very big ebook stores, an excellent Audible replacement(with huge superproductions involving famous Polish actors voicing the lines being made regularly), instead of Amazon and Ebay we have Allegro(which in my personal opinion has leapfrogged ebay by about a century worth of development, it's just a much nicer experience). Ebay tried entering the Polish market a few times with huge marketing campaigns and lots of deals, but Allegro's dominance is just so untouchable that I think they have just given up now. I suspect Amazon doesn't even try for the same reason - it's not even localized to Polish(although Polish customers can still order items from any Amazon site, they get delivered to Poland without any issues and for free if you have Prime).