This is one of my favorite shoulder pressing variations. It's not only a great way to spice up your shoulder workouts and hit your shoulders a bit differently, but it also requires some additional core muscle engagement in order to maintain the offset load.
Although you can certainly perform this exercise using a dumbbell, do it with a kettlebell because its design really works well for this exercise.
You probably never thought about it, but most people can't produce as much force using two bilateral limbs to perform an exercise as they can if they perform the exercise with each limb individually and then add together the force of each side. It's called the bilateral deficit and you should take advantage of it to pack on some muscle.
The bar placement in the Zercher squat makes it a lot easier to activate the core and control the low back and pelvis. A straight bar without chains will work too.