Where can I apply in person?
In any registry office in Poland.
where (...) I can apply in person
a decision on the confirmation of Polish citizenship or its loss shall be issued to the interested party or to an entity with a proven legal interest or obliged to receive the decision, by a Voivode competent for the place of residence or the last place of residence on the territory of the Republic of Poland of the interested party; should this ground be lacking, the decision is issued by the Masovian Voivode. A decision by a Voivode may be appealed to the Minister of Interior.archiwum.mswia.gov.pl/en/document/ways-of-acquiring-poli/797,Confirmation-of-Polish-citizenship-or-its-loss.html
and how
Only in Polish:
gov.pl/web/mswia/potwierdzenie-posiadania-lub-utraty-obywatelstwa-polskiego