Although it's a fun project per se, it looks totally useless from a user's POV. Just saying.
Technically, "levitating" objects using controlled coils has been done for decades. I remember an old electronics book I had when I was a teen that had a project like this (only without the added wireless power transfer...) It was a relatively simple circuit too AFAIR. Add to that wireless power transfer such as Qi, and you're done.
But again, since the levitating object has to be pretty close to the "controller", beyond the fun effect, I find this absolutely useless.