Popcorn lung does not come from vaping any sort of regular vape juice that is on the market anymore. Popcorn lung came from inhaling vape juices that had Diacetyl, or Vitamin E acetate. These were used for flavoring in the early days of vapes before it was found out that they cause popcorn lung. It was also more common in THC vapes than nicotine ones.
I haven’t heard of one case of it happening since then, as all of the vape juice manufacturers stopped adding these ingredients years ago. I’m not saying vaping isn’t bad for you, it definitely is, but popcorn lung is not something anyone needs to be concerned about anymore. It is definitely not as bad for your health as smoking cigarettes, at least.
You are correct that gum or nicotine pouches are the least damaging way to consume nicotine.