Is this eSIM valid for neighboring countries like Germany, Czechia, or Ukraine?

 This specific plan is valid only within Poland (or, if it's a regional plan, you'd say "Yes"). This is a critical point. If you take a train from Krakow to Prague (Czechia) or from Warsaw to Berlin (Germany), your connection will stop. If you cross into Ukraine, it definitely will not work (as it's non-EU). For a seamless trip, we highly recommend our Europe Regional eSIM, which covers all these countries.