I think Fox but maybe not a Sprite. Pics I can find show solid tube forks on Sprites. The one in my pic appears to have front suspension. Maybe a Doodle bug or Trail Bug? The mounts for a jack shaft might be on all three models, even if not equipped with the jack shaft?
I see the remains of blue paint on the frame, under where the seat would be, might it have been blue originally?
I have not seen it in person, yet.