It's pretty much a blender with a tank, a heating function and self-cleaning. It has different options for different type of plant milks, which (I suppose) change how much it heats the water and how long it blends everything. Which is pretty much what they do for the store bought oat milk as well.
What makes the biggest difference in taste though is not the maker itself (although it does make a difference) but using Amylase when you're done blending. It's an enzyme that breaks starch into sugar. Without it the oat milk will probably be pretty thick or even kind of slimy. As far as I know it is also used in store bought milk to give it a natural sweetness.
I have a Springlane plantmilk maker. It was just under 200€. Can't speak for the brand in general but I have the maker since last year and I am still happy with it.
You don't necessarily need to declare enzymes in food manufacturing. They are consumed/used/deactivated before the final product. They would be listed as "processing aids" in the process description, just like pH adjustment chemicals, activated carbon treatment, antifoamer, etc.