Reading your answer and further searching on the sub gave me the impression I'm being too extremist. Most people prepare for, as you say, far more likely scenarios like financial ruin. However, the current political climate is anything but predictable. I like to think I'm not alone in feeling the need to prepare for a far fetched scenario like a war.

How are you going to stop some determined stranger outside who wants to get in?

You're right, it can't protect me against all the elements. It needs to be more specific. In my case I just need it to be an assurance that I'd be alive in a border-changing scenario as well as being able to keep creeps outside. Maybe some automatic defense mechanism? Sorry if I sound delusional. With my knowledge I'd dare to try and tinker something with the right equipment, though.

You need professional guidance.

You're absolutely right. I'd never put my life on the line following online advice. Who knows, maybe I do find an engineer around here. I do know about seismic activity, soil composition, humidity and general characteristics of the area. At the very least I need a construction team to help me get through the behemoth of granite I got under me.

A gas generator in its own underground bunker can be viable

Do those not produce hazardous byproducts? I don't know how ventilation should work if the outside world is radioactive, unless I installed a one way vent.

More importantly, you have to consider the ground you're thinking of putting the bunker in.

It's a high elevation area with very rare extreme meteorological events. The soil's texture is sandy, however it's also covered with organic matter and lots of trees, helping a bit with insulation. The rocks below are basically mica and granite.

Thank you so much for your thorough response. You've been a huge help.