If the air from within the phone was evacuated, notionally because the phone is not assembled in a gas tight manner, the air within the phone would be drawn out during the vacuum process.

The numbers I listed above are for sea level atmospheric pressure. I wasn't working with hypothetical numbers that didn't regard atmospheric pressure.

That means that the volume of the phone would be fixed by the rigid exterior and there would be no gas pressure inside the phone's envelope to oppose atmospheric pressure acting on the faces of the bag.

There would be a 1 atmosphere differential between the screen and the interior of the phone. Well, a bit less than 1atm if the chamber was drawn down to 100mbar.

1 atmosphere is not that minimal. It's 14.7psia which means that we have 14.7 pounds per square inch acting upon us.

I agree that atmospheric pressure isn't all that high in comparison to a can of spray paint (somewhere around 70psi), but I still don't see that exerting 200lbs of compression on a phone is a great thing to do.

Perhaps the thing that is saving the phone is that the bag may not have been very tight against the phone when the chamber was drawn down. Usually you have to draw vacuum for 90s to get a bag drawn down really tight (well below 100mbar).

It could be that the volume that was trapped in the bag before the seal bar hit was still considerably larger than the phone. The chamber might have been drawn down to 100mbar, but the starting volume (phone plus loose bag gap) could be double the phone's volume so the bag's final pressure is considerably higher than 100mbar. I've found that if I really want to get a bag tight I've got to draw vacuum for awhile to account for the bag starting a bit slack around the object.

I've actually designed vacuum pressure systems for degassing polymer resins and adhesives. I am a mechanical engineer who designs products.