Several reliable digital libraries host extensive collections of Pashto literature:
Moving into the modern era, Ghani Khan (son of Bacha Khan) brought a revolutionary flavor to Pashto poetry. He combined Western education with Pashtun roots, writing about the beauty of the universe, the hypocrisy of society, and the "madness" of love.
If you are looking for specific authors, these are the most common collections available for free: Abdul Ghani Khan
Here are the best digital libraries and sources: