You can use any frozen wontons or potstickers. We like the smaller ones for soup and found mini wontons (chicken and vegetable) at our local grocery store.
In our experience, fresh ginger root is best for this recipe. You could substitute, but you will need a LOT less, as ground ginger is much more potent.
Baby bok choy and regular bok choy are essentially the same aside from their size. We like the baby bok choy in this soup because it doesn’t really require cutting and you can drop them in whole. You can use regular bok choy if desired; you will just need to cut the leaves off the stalk so that both ends will fit into the pot.
We use a concentrated bouillon base for most of our recipes instead of broth or stock. It’s convenient, takes up a lot less space, has a more intense flavor, and is easily reconstituted with water. We listed broth in this recipe, but we actually used chicken base and water. You can certainly use broth or stock. A note about chicken base: it can be saltier than stock depending on how much you use (plus water).