That's, what, 30 000 Pa of overpressure?
So, 1,3 atmosphere. If my calculation is correct, that's around 85 000 N of force on an opening with 60 cm diameter (something a person might crawl through). I would not mess around with those forces and the thing pictured in your first post most definitely could not withstand that pressure, even if you could seal the door itself.
Controlling the pump and a release valve is doable with arduino, but not advisable for this purpose in DIY method.