From the article it looks like the trailer can push, when needed:
"The eStream has the potential to torque-vector and help stabilize not just the trailer but the tow vehicle together with it, aiding a smooth, stable tow in sway conditions or side winds. It also has the potential to actually help with traction—up muddy or snow-packed inclines, for instance."
Stabilizing is a matter of controlling the difference between left and right side torque (which is popularly called "torque vectoring" now) - that can be braking, or driving at any level. Current production vehicles here are required to have stability control, and that is executed mostly with application of individual brakes, although drive power is managed as well. Just as motor vehicle stability control logic is adjusted to accommodate an attached trailer, a trailer could contribute to stabilizing the tow vehicle by only braking or by distributing torque side-to-side appropriately without ever pushing forward on the tow vehicle.
Just providing all of the driving force needed to move the trailer would certainly help with traction, without actually pushing on the tow vehicle; the quoted text does not say anything about pushing. Of course it
could actually push, although that would never be needed in any circumstance (because the trailer won't have better tractive force to mass ratio than the tow vehicle unless someone is towing an extremely expensive Airstream with all-wheel-drive using a two-wheel-drive tug
) and would be stupid at any significant speed.
I would call it a pusher trailer because it is actually pushing itself down the road and at least occasionally, for very good rational reasons, pushing the tow vehicle as well.
Pushing itself makes it a powered trailer, of which there have been many over the decades. A pusher trailer would actually have to push the tow vehicle, and in the context of EVs it means a trailer with the primary purpose of pushing... which is certainly not the case here.
www.greencarreports.com
It has drive wheels, 900W of solar, and 80kWh of batteries! It appears some kind of connection senses the towing and braking forces at the tongue to power or regen brake the drive wheels. Something like the mechanical action of typical trailer surge brakes.
