I used to go with pastels on hikes. I made a small soft pastel – press/drawing-board using stretchy rope and hardboard with slits in the corners. I would wrap the stretchy rope around the slits to clamp the work in between the boards and interleave with teflon release paper. I could throw the pastel around with no damage. Soft pastels can take quite a lot of down ward pressure. You can literally drive a car over the board….but not over glass.

Point is that I see no issues unless the glass breaks.

Acrylic won’t break, but it can hold quite a static charge, and that isn’t the best for soft pastels.