The last sitting House member to be nominated for president (and win election) was James Garfield in 1880. AOC hasn't even been a ranking member of any House committee. She is highly unlikely to overcome these hurdles.

Certainly hurdles, but not insurmountable. The last person to be nominated for President and win election who hadn't held a government position used to be Herbert Hoover, but a century later we saw what happened. If AOC runs, it will be because she's found enough support among her side of the party despite her lack of experience.

And I don't see why you define Pritzker as progressive left.

Because he's positioning himself to run in that lane. Just like Gavin Newsom has tried to position himself for a more centrist lane (despite him probably being among the more progressive politicians in the field) by making some moves in that direction, Pritzker has been doing the same on the left. He's championed progressive causes, extensively supported progressive candidates, and shaped his policy positions to entirely match those of the Sanders-Warren pattern. He's clearly indicating that his campaign strategy is to try to run in that lane of the party.

It might not be successful - after all, you're fairly up to date on politics, and you don't think he's any more progressive than Whitmer (who progressives would never choose over a candidate like AOC in a million years). But that's been what he's aiming for.