The PNCC are an American church, an 1890s immigrant schism (in ways parallelling the Alexis Toth incident that jump-started Russian Orthodoxy in the lower 48 American states - perceived mistreatment of Slavic immigrants by Irish bishops) that after the fact came up with reasons to justify themselves (rejecting the Pope, etc.).
The real causes of its founding seem to be understandable reaction to injustice mixed with mistaking nationalism/ethnicity for the faith - something one sees in other immigrant schisms. (And when the descendants of the immigrants assimilate, that pretty much dooms the group - a dead end.)
They are the only
real Old Catholic group in America - part of the communion of Utrecht, The Netherlands. The rest are fakes - vagantes
There were Lithuanian and Slovak groups that similarly broke off and eventually joined the PNCC. And a handful of Italian groups started the same way but eventually joined the Episcopal Church - here's one of them
Its founder, rebellious Polish immigrant priest turned Old Catholic bishop Francis Hodur, had some strange ideas. He apparently believed in a kind of universalism (denial of an eternal hell), considered Baptism and Confirmation one sacrament, counted 'the hearing of the word of God' as one of the seven sacraments and considered Confession optional.
In 1946 the PNCC, still led by Hodur (he died in the 1950s), and the Episcopal Church declared themselves in full communion - earlier, in 1930, the Church of England and the Old Catholics in Europe did the same thing. To their credit, the PNCC terminated this in 1977 after the Episcopal Church approved the attempted ordination of women.
Old Catholics in Europe - real ones! (a rump sect really) - now ordain women. The PNCC doesn't, and is in 'impaired communion' with these other Old Catholics. Despite their late founder's strange beliefs and their former Episcopal ties, among Old Catholics they seem amazingly orthodox.
Their popular devotions are all RC and they don't canonize their own saints, though you might see Polish and American secular heroes such as Copernicus and Lincoln in their stained-glass windows.
The PNCC allows men to marry after ordination and has married bishops - just like the Episcopal Church.
Another distinguishing feature, coming from the immigrants' battles with RC bishops, is that each parish church owns its property.
The PNCC has a history of some liturgical experimentation like Mass facing the 'wrong' way (the congregation) - they started doing that in the 1930s - but this seems to have been balanced by the Poles' cultural conservatism. For a long time they were doing the Tridentine Mass and other traditional RC services translated into Polish (the language reinforcing the whole nationalist/ethnic raison d'etre
) but now they use slightly modified copies of the Novus Ordo
and other modern Roman services.
It has a tiny following today - most Polish immigrants didn't join it so it never really was big - and its original, real reason to exist is really gone as its members are English-speaking, born Americans.
But unlike vagantes
it can be said to be a real church with real congregations, though small, and generational members.
They seem based in the same Rust Belt heartland in Pennsylvania as what is now the OCA - both groups of Slavic immigrant workers.
Rome recognizes their sacraments and, reinforced by a recent written agreement, PNCs living away from their churches have an open invitation to RC Communion, Confession, Unction, etc. (which unlike the Eastern Orthodox, the PNCC approves).
As for the Eastern Orthodox, the PNCC technically are a big unknown just like any other non-Orthodox church. I imagine, though, in practice there is de facto
recognition of 'validity' but of course no intercommunion, just like with RCs.
My guess is this little group might not exist in two generations, and a goodly number of their faithful simply will be reabsorbed into the RC Church... much like the attrition in the OCA, ACROD (whose founding also parallels the PNCC's except theirs was in the 1930s) and the Ruthenian and Ukrainian Catholic churches (who likewise become RC) in the same part of the country (which people are leaving).