So another 'Italian' could form in the Americas through koineization, just like
Hunsrik formed from the variety of German languages present in Brazil and took a different direction than German did in Europe.
The challenge for that kind of scenario is that you would need a settlement history for this region where speakers of a given set of non-Iberian dialects would predominate, enough to be able to set at least local norms. Even then, as the history of Hunsrik shows, this situation is deeply vulnerable to changes in the wider country.
There needs to be an actual Italian colony. Not a city with lots of Italians in it, but city founded by and for Italians, where that is the official language. Otherwise they will just assimilate to whatever the official language is, as IOTL.
More, it needs to be a substantial city, a metropolis capable of supporting a diverse economy. A relatively thinly-scattered rural population might keep a language going for quite a while, but if the language has no presence in urban areas it faces a from prospect. In the Maritimes, for instance, the Francophone Acadians have put great energy into developing Greater Moncton as a bilingual city.
This is also why we do not see enclaves of Catalan or Basque speakers in Latin America, or Welsh/Irish speakers in North America, despite many immigrants from those communities. Immigration is not enough. You need to create a legal status for the language.
I am not sure about that. In the case of Catalonia and Wales, for instance, their early success at industrialization meant that these regions had become regions of net immigration at a relatively early date. More, there were relatively few speakers of Welsh and Basque and Catalan, enough that they could easily be missed among the much larger masses of British and Spanish emigrants. That these populations were not necessarily that substantially distinct from their neighbours—Welsh Protestantism fit squarely into British traditions—aided the assimilation.
In the particular case of Irish, the speakers of the language really seem to have been disinterested in its survival by the 19th century. Apparently some speakers of Irish were surprised, when they encountered speakers of Scots Gaelic, to hear that language still being actively spoken. Language seems to have been deprioritized as an element of Irish identity; in the 19th century, religion took over.