Thank you for that very detailed explanation!
One other thing about putting computer devices in the luggage compartment... I seem to recall that devices containing lithium batteries are supposed to be in carry-on, never checked, because something about the luggage compartment causes them to fail catastrophically. So now, those airlines are requiring these devices be checked. It seems to me that they could be risking fires in the luggage compartment. Or not... the air is pretty thin up there.
The baggage compartment is at no different pressure than the cabin. The entire fuselage of the aircraft is a tube that is pressurized. The tube is easier to keep pressurized than any other shape. . . think what would happen to toothpaste tubes in your check baggage if they weren't pressurized. The toothpaste would be all over your clothes. That's why propane and oxygen tanks are always tubular. Same with the planes. Who ever made that claim about the baggage compartment and Lithium batteries probably thought that the baggage compartments were not pressurized.