This is what I accomplished today. The one on the left took about 30 minutes to assemble, mostly because I was eating lunch and screwing around while doing it.
The one on the right took almost 2 hours, much of it consumed by hunting for the right tools to overcome defects in the parts provided. Piss poor design and piss poor quality control.
The rear axle would not go through until I filed out one of the holes because they were misaligned. The handle takes 13 (!) screws to assemble, basically because the pieces are warped enough that you need a screw every 3 inches in order to make it fit tight.
I hope my son likes them, but tbh he won’t want to sit still long enough to ride in either probably. He prefers walking / running on his own.