As the German Wüstendrachen had little impact on the war anywhere but in Africa, Allied planners tended to dismiss them as either a stunt designed to show the impressive reach of the Reich, or a poorly-conceived plan to create a new form of wonder-soldier to compete (in general, poorly) with powered-armor equipped heavy infantry.
In fact, neither of those was the strategic purpose of the Wüstendrachen, which was in general never realized.
By the time the Reich had determined victory had to mean conquering North and South America, the reality of logistics just invading the Soviet Union and Czarist Crimea had become clear. While invasions of the Americas wouldn’t have to deal with Russian Winter, the need to import the needed war materiel across one or more oceans was seen as a major problem. Even if jet bombers and saucers could destroy most of the continent’s opposing forces from the air, truly controlling such territory would require troops on the ground.
This is where the drachen were seen as part of the solution. The beasts were capable of outrunning and outlasting horses, camels, and even jeeps, could allow expert troops to carry significant materiel and even anti-tank weapons, and while they could not compete with walkers or heavy infantry, they were more than capable of handling light infantry or militias.
And they could breed.
The idea was that a well-blooded, well-trained Wüstendrachen could expand exponentially once established on a foreign continent. A single female could lay 4-5 eggs a week, and hatchlings were born nearly self-sufficient. They would imprint upon birth with a pack handler, could be used as guard animals within a week, and could become mounts within 3 months.
Rather than have to build factories, import or process fuel, maintain supply lines of tires and spare parts, the plan was for elite Wüstendrachen to establish bases of operations, feed their mounts on fallen foes and wild game, and recruit, train, and educate local whites to become volkwüstendrachen, creating a self-sustaining, replicating, self-sufficient scouting and patrol force that could spread across any continent with little support from Germany.
Though the project only took root in any strength under Rommel in Africa, its success there for years suggests it would have at least had some impact on an invasion of the Americas, if the Reich had ever managed great enough success to attempt such a thing.