Sounds like you found it! Good work!

Misfires sometimes take a while to surface if an injector is marginal. It might only fault at higher throttle, and the fault takes multiple occurrences to get set. Your process was solid, though.

The P0446 is probably unrelated, though, right? As others have said, it's a venting issue. Checking solenoids is the start, but if your carbon canister is clogged, it can do this by itself. Also, try other pumps.

Nozzles are all over the place in their capability. When I was still at GM, we thought we had an issue with the (then) new C7 Corvette and fueling. It was just one gas station causing the concern, near Warren Tech Center, but their nozzles were junk.