You need to have the hardware set up ahead of time.

https://xkcd.com/644/

Buy a new hard drive/SSD for your Linux installation. Put your Windows drive away in a drawer so all of its contents are saved, and you can swap it back in if you have to. A USB adapter can be helpful for retrieving files.

LoRA is sort of a slower version of wifi and as such, you should assume Meshtastic is monitored, at least for traffic metadata. The actual messages are encrypted though.

Use of ham radio for this type of thing, or with any type of encryption, is against the ham regulations, though depending on how it is done it could be made hard to detect.

There is actually still such a thing as a satellite pager, a receive-only device that can get pages that cover regions as big as small countries. They stopped making the receivers quite a while back, but some are still around and the subscriptions are still available, though expensive. This info is itself some years old so maybe they are all gone by now.

POCSAG pagers still exist in the US too, though again, they are quite expensive compared to cell phones. Their main attraction is supposed to be higher reliability, so e.g. doctors can get paged even with the mobile phone network is out. I don’t know if that advantage still exists. In the more distant past there was something called ARDIS which I think is gone now. That was quite a robust signal, so you could get paged even in sub-basements of buildings and places where mobile phones didn’t work. Repair technicians who worked in those places often carried them.

I’ve followed this stuff slightly as it’s interesting for the reasons you say, but I’d have to say it’s not really cost effective for most of us. POCSAG in particular only works in relatively localized areas like single countries. I know a guy who would want something like it, but only if it worked pretty much everywhere, since he travels a lot.