I actually have an avo tree taller than me that I started this way 10 or so years ago. It is in a pot, and our climate is a bit cold for them, so I move it into the house in winter.
These are normally outside, just hiding from the worst of the winter.
You can graft branches from good producers onto your plant.
Not sure where to source the grafts though
Generally you just buy a tree pre-grafted. They’re usually grafting onto heartier root stock to begin with.