You can get the Portuguese nationality if your father or your grandfather was Portuguese.
Can I get the Portuguese citizenship if my father was born in Guinea Bissau when it was a Portuguese Colony?
My father was born in Guinea Bissau when it was under the Portuguese colonization. His parents were living there at the time. He has his birth certificate stating the same. What is the process for me to pursue Portuguese citizenship?
In theory, that would be possible. However, it is only possible to give you a proper answer after analyzing the documents you have.