Wow the more I read the more it got off topic. Domiko…your great grandfather was a Rusyn/Rusnak like mine was. Eventhough my ggrandfather came from present-day village Velka Trna in southeastern Slovakia the evidence of being Rusyn is the fact that they were GREEK CATHOLIC. All Greek Catholics in history were Rusyn ethnicity.
I believe Rusnaks are the type of Rusyns that speak a Rusyn/Slovak mixed-language living in eastern Slovakia. Or perhaps Rusnak is just a synonym for Rusyn. Either way, “rus” is in both words…
Also, whoever said your ggrandfather was a Pole is ignorant. Poles were never Greek Catholic.
You should join the Facebook group “Carpatho-Rusyns Everywhere! group”. I learned a lot about my heritage through the help of members there.