alternatehistory.com

POD: October of 1944, US Navy deploys carrier variant of the P-59 Airacomet to Leyte Gulf, making it the first jet aircraft deployed to the Pacific Theater, as well as the first allied jet-powered fighter.

I have no idea what would happen in this timeline, but it could (theoretically) push jet development forward, maybe even to 6th Generation fighters being deployed in the current time.
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