My first though was perhaps you could look for a semi transparent coating to scratch off, but that would decrease the drama of the revelation of what is behind, so that’s not necessarily a good idea.

In this video at least I can’t make out what the drawing itself is, but I do over time get to start to see more of you.
I do get quite engaged in seeing more of you, but for the majority of this clip you are obscured. Meaning you are just as obscured from the audience as when you had your back to them drawing.
I might suggest using thicker lines though.

Also very theatrical is seeing your legs, I’m not sure where to go with that, but it’s interesting, some relationship of this exposed portion of yourself, with the revelation of the rest of yourself could be very dramatic, A narrower drawing surface that allowed you to see over the drawing as well could be interesting.

I though the movement of the bottles would be very interesting and it fact they really were, I’d love to see more made of that, or even more lines an pulleys. Not sure what practical function those lines a pulleys would have but they would look great.

My most dramatic inclination upon seeing this (driven my my puppetry interests, and not really very connected to your intentions.) Would be to have two puppets, one with a scraper to scrape holes in the medium, and one with a paintbrush who could attempt to re-cover the wholes. And lots of peaking and relieving of the puppets and the puppeteers.
Probably not directly reliant, but you did mention that if you were really scraping holes in the medium that you would need to do that and then peak through those holes. I did not see that in this simulation because you didn’t have to peak, but it would be dramatic, and accentuate the interest in the revelation of yourself to the audience.
Perhaps the drawing should include a silhouette that you eventually have your body conform to.
Perhaps it should include areas to peak through that seem appropriate or inappropriate for a face to appear, thus having comic value when you peak through those areas.

I mentioned before that I thought it would be interesting to see you create a drawing with the intent to create music, and to see someone draw a drawing with an intent to draw something, while listening to the music it happened to create.
The product and by-product would be swapped in each case, each byproduct having it’s own emergent form and value.

I could also see extending that further, and reverse the process, where you have sound analysis drive the pulleys, and thus draw a picture. (or just have it draw a digital image which would be easier if less dramatic)
Then have someone create music with the intent of creating a picture, and someone create music with the intent of creating music that happens to draw a picture as it’s byproduct.

all four might not be equally interesting or effective, but the presentation of them may enhance the meaning of the primary mode of drawing with intent to create music.