how to see what app is available in what region app store

i will give you example i want to download rezultati.com on my app store and my region is on usa so i cant find it but i ask developers and they said me i need to change to croatia and i did it and i get app but i see some cool apps on internet and i wanna to download it but i dont know what region it is available how to see what app is available in which region answer pls thx