I made a quick insulation removal tutorial, in case it helps anyone
https://youtube.com/shorts/hK4GvvyINFs?
These are just my tips, other people have their own suggestions and preferences. Keep in mind your own situation, safety, abilities, etc
~~~~From the video~~~~
Removing old insulation is not always necessary, but you might want to consider it if your bus might have mold, you plan on expanding the depth of your walls, or if you don't want debatably harmful fiberglass insulation particulates in your air.
Keep air movement minimal during removal to avoid how much gets on your skin, in your eyes, etc.
Cover your important parts to the best of your ability, most importantly your respiratory system with a dust mask, respirator, triple bandana, etc, something is better than nothing. I really can't stress enough how awful it is when this gets in your eyes, so some kind of eye protection is great. Then gloves, coveralls, etc.
Vacuum as much as you can after removal or else it will become "permanent" in the next step.
I use spray paint to cover any remaining insulation or leftover glue that remains. This leaves a protective layer that hopefully limits any further particulates after the scraping step. Make sure to leave ample time for it to air out, hours for breathability, days for spray foam, weeks before adding walls.
After you're done leave a fan on for a few hours with as many doors and windows left open. When you come back later, turn off the fan and do another vacuuming session.
Lots of it will stick to your clothes and skin, so I strongly suggest removing extraneous outer layers outside then showering/changing asap. You don't want to track this into your house.
Lastly, I strongly suggest documenting your process and giving any further tips to others in our community on skoolie.net, YT, etc.