It allows for worldwide comms, even in situations where entire infrastructures cease to exist. This is especially useful for emergency situations.

There are many, many digital modes on ham radio. The encryption question is one of legality – not capability. But the short answer is yes, you can do various things with data on ham radio.

I guess it’s a question of the level of disaster / political strife / etc which causes the internet to no longer be usable.

Edit: worth noting that mesh is effectively a kind of ham radio device, which uses some ham spectra and can be subject to the same rules about encryption (it is specifically illegal in the US to use “messages encoded for the purpose of obscuring their meaning”, FCC Title 47 Section 97.113). Digital signing, for example, does not violate this.

The only reason you don’t need a license for mesh is because it is using specific, reduced power transmissions and specific parts of the spectra. Adjusting these settings beyond the acceptable range (e.g. boosting output power) would mean you need a license just like any other ham device.

Here’s an example of intercepting and transmitting mesh content using an off-the-shelf ham radio SDR.