400 hPa is about what you have at 7000 meters, and no pressurization.
750 to 800 is about what they shoot for in level flight; see the graph in my first link.
The units millibars and hectoPascals are close enough as to make no difference.
I was talking about a backup pressurization controller that manages cabin altitude crudely but tolerably given a more-or-less normal supply of incoming air. You’re talking about a rapid decompression such as would occur after a big hole appeared in the hull. Two rather different scenarios.
But yes, having a big hole in the hull does lead to lots of ear and innards effects very quickly. None of which are much fun. But not life-threatening in and of themselves.
It occurs to me that by rights Champagne and the like “should be” banned from hand luggage, given all the other nonsense that’s confiscated.
In the US, a bottle of champagne wouldn’t be allowed through the security checkpoint, but a passenger could buy it from one of the shops in the secured area; bottles of champagne aren’t generally regarded as a security threat.
A number of jokes could be made about hijacking scenarios with gourmet terrorists, but it’ so felony in front of TSA and today’s 9/11.
I don’t often hijack planes, but when I do, I insist on Dom Pérignon.
Make it a less than three-ounce bottle with a wee little cork in it.