Another example occurred to me:
Almost all fixed wing aircraft have the engine providing thrust along the longitudinal axis, give or take.
Yet somehow all these aircraft manage to overcome gravity by producing a force by extracting energy from the airflow and generating a force - in this case lift.
I don't see anyone claiming the effect of a wing is to reduce the weight of the aircraft, we all accept that lift is a force, despite there being no thrust applied vertically.
So the idea that a winglet - a more-or-less vertically oriented wing, with a bit of toe-out - can generate a similar force, in the forward direction, is not so strange, surely.
Traditionally, forces acting in the forward direction are called "thrust".