I've done some research and stumbled across the following (maybe unofficial) url which is used to query app details from android play store. But based on the unofficial google market api I guess this one is using authentication token
http://android.clients.google.com/market/api/ApiRequest
There is obviously a way to request android app details without logging into ones google account - that's how Google play site works when browsed in a web browser.
I was unable to find any guidance on how to actually do that.
The project I develop cannot have any unofficial libraries or codes in it, it also cannot use any private android API.
I also came up to the following link, which obviously is not an official google api link (in other words not 100% trustworthy that it wouldn't change without prior notice)
https://androidquery.appspot.com/api/market?app=(put the package name here)
But I guess any possible solution should be something similar to what this link is internally performing.
So, how to construct a valid request to google play store to retrieve app info (request url, parameters, parameter formats, cookies, etc.)?