"Mind Blown" Effect / Remove top of head

I'm trying to create an effect where the top of the user's head explodes and objects fly out of it, like this:

My questions are:

1.) Is it possible to remove only the top portion of the user's head, either via segmentation, occlusion, or some other method?
2.) If if possible to segment the head, is it possible to fill the remaining background space with the user's background via camera texture, or should i segment out the background and use a custom texture?

Any help/advice is appreciated! Just getting my feet wet with this AR stuff.

Thanks!