Mount a ring of fans (e.g. laptop fans) on a hat/headband/crown to provide airflow away from the user's head.
Until I get more models built I'm using a simple example from Thingiverse; imagine the "flower" being one of a series of fants mounted on the headband, and assume a tiny microcontroller (micro-arduino of some sort) + battery + switch.
(Suggested during converation with George Kondraske at UTA)
Another idea (related) a COVID19 "snorkel" .
Imagine pointing the fan the other way on the "camping hat" fan (also solar powered, as it turns out).