Hi and welcome to Pianostreet,
An all in one device is easy to setup but leaves much to be desired in terms of quality. Considering how many music educators have suddenly been faced with the prospect of delivering online lessons, it probably still is the most appropriate option for those getting started in online teaching. I think one should first understand the basic concepts of the workflow before moving to more elaborate setups. Both teacher and student have a responsibility for getting the technical aspects of this running smoothly, as a deficiency on one end can lead to a lesser experience by the person on the other end. Realize the quality you receive on your end can only be as good as what your student is putting out on their end.
Using your student's current equipment, instruct your student on placing their camera and microphone. Experiment with placement. A change in position can make a huge difference in sound and video.
In terms of quality, if you want your sound and video to improve over what you can get with a laptop or tablet all-in-one solution, you will need to start separating the components. A USB microphone, or even better studio microphones to mic the piano and a vocal mic for talking. A camera with a better sensor than available on a webcam.
The optimal place for the piano mic, vocal mic, camera and screen are not in the same place. So separating the components will generally yield a better user experience. You can place the screen in front of you where it is easier to see and the camera to the side where your student has a better view of the keys. Piano mics optimally placed to pickup the piano, and a vocal mic close to you for voice pickup.