Can I apply for a passport in Ireland/the US while on holiday?

I’m temporarily in the USA but normally live in another country; can I apply for an Irish passport here?

No, you must apply in the country you are normally resident in.

You should only apply for a passport at the Consulate General of Ireland in Boston if your permanent/legal place of residence is Massachusetts, Maine, Vermont, New Hampshire, or Rhode Island, or in the case of a lost/stolen passport while visiting here.