Good summary. I think you captured the “spread” tendency that is characteristic of Protestant communions. Time after time, a group of sincere Christians wants to preserve, or restore, the fullness of Catholic belief, but without some recent innovations by Rome. So they say, “we accept everything before X date, but reject as unscriptural or untraditional Rome’s actions or doctrines since then”.
Anglicans said Rome was mostly ok until just a few years before Anglicanism. Lutherans push the date when Rome went off track somewhat earlier, etc. Calvinist traditions push X date, when Rome went off track, even earlier. The Old Catholics, like the others, were united at first. They said Rome went off track more recently. But inevitably they respond to modern times by rejecting half the beliefs held by their founders, and much of the beliefs held by fellow Old Catholics. The same pattern as Protestantism.
The PNCC was started when Polish immigrants felt their needs were ignored by Irish bishops in the USA. Later, they connected with Old Catholics, to establish apostolic succession. Since their Polish ethnic base is assimilating, they now brand themselves as “NCC”, and, where I live, try to recruit any Catholics who have a grudge with the local bishop. I don’t have a problem with individuals, including Lutherans on CAF, who choose to identify as Catholic. I do have a problem with churches that use that term as a recruitment. That said, I think ecumenical efforts with the PNCC have potential, though not with the liberal wings of Old Catholics (I. e. abortion, marriage, etc).