pixel popping crop to head. original pixels, not resampled. Normal image settings, no noise reduction or other processing.

The speck above the bill seems separated so I am inclined to say it's not feather, but rather something in background. In any case not clear enough to clearly say it is feather.

So to summarize: This will likely remain equivocal on species. I do agree that Empidonax is the likely answer. Nothing I see contradicts Least Flycatcher. BNA describes its eye ring as distinct but sometimes less than complete. Also described as the the least green of Empidonax. But failing to disprove is of course not the same as proving.

As to Wood Pewee, whether there are whisker feathers in the image is at best unclear. The eye ring and the primary extension of less than 1/2 tail would seem to contradict.