Canada

So on a second read, I think you might be talking about a situation where the government still allows an alternate system to operate, at least if it's established. I already wrote this up from the same worst-case perspective as in OP.

For daily driving, the trick with that would be offering something commercial providers can't, other than an abstract long-term argument. Without that, you're basically just trying to start your own ISP, but without any investors. For enthusiast use, see APRS below, which is a thing.

APRS is kind of the relevant current standard. The trick is that being carried by radios that are unpredictable, it has no upper bound on latency (I think). If you want the same browsing experience (TCP especially needs a lot of back and forth) that's really hard, because presumably big brother isn't going to let you have a mesh station online for very long.

The burst thing I was talking about is genuinely how spies do it in locked-down places like Eritrea or Turkmenistan - you go to a busy public place and absolutely hog bandwidth for just one second, using a disguised radio, and then wander out with your groceries before the radio detectors can catch up. I suppose open-source resources for that would be good, if they don't already exist.

I'd love to look at the transport layer of NATO's system. It's designed for both wartime (so arbitrary failure rate, type and pattern) and extensibility, and I'd be fascinated to know how they did it. Unfortunately, it's also a big damn secret, to the point it's the main thing they bring up when the media asks about China getting their hands on a working F-35. I'd also anticipate that it relies on every user registered as friendly acting friendly, at least over the long term.

One of the things that's on my future project list is over-the-air crypto, so you can pay someone to transmit your 50 meg thoughtcrime video slowly but persistently. As far as I know there's no prohibition on digital sigs (like there is on encryption), so it should be doable somehow.