Confirmed miles + points upgrades on BOS-EZE?
I apologize in advance for my lack of knowledge on this, I tend to fly United domestically and just purchase the cabin I'm looking to fly in, so I don't know if this exists.
I am looking to fly BOS-EZE, ideally through EWR on the Polaris EWR-EZE flight this summer. I typically do this route through JFK on AA, buying economy, and then using EF to find out which JFK-EZE flights have confirmable upgrades for $300+25k miles each way, calling AA, paying for the upgrade, very straightforward.
Does United have something similar, where I can find out which days/flights I could purchase a confirmed upgrade from an economy ticket? If so, can I find that info on EF, and lastly, what does it cost if it exists?