Hmm.
Paid critique could work well, if coupled with edits and a satisfactory wealth of paragraphs, littered with examples. If you are the teacher, you could include screen recorded videos explaining the process. This and post-critique edits and guidance could fashion a nice, compact sized package.
I don't think one hour screen share sessions could aid most people, seeing as pixel art is somewhat time consuming for the inexperienced, and especially if the teacher is aiding the student as he draws. Perhaps it could work if both are physically present, but that will not usually be the case.
But I could easily do it if I wanted.