It would have to be in a single district; attempting multiple would definitely fail.

NZ has had a number of individual electorates where the Greens* won the seat, Labour came second, and National 3rd. With a sufficiently left-wing area and a galvanised base, it’s possible.

• Note: NZ greens definitely are not the same as the US Russian plants.

It is possible for a third party to arise in FPTP elections, but it’s certainly not common or easy. The UK has a bunch; NZ had a couple before moving to MMP; I think Australia has some.

It usually requires a competent and well-known politician storming out of their party for ideological differences, but being locally popular enough to win their seat as an independent or new party.

AOC might pull it off.