Are there war-resistant networks citizens can join?

The European Union is slowly waking up to the fact that the US might not continue protecting it (a Republican senator introducing a bill to exit NATO, a new security direction talking about breaking up the EU) and the possibility of a Russian invasion. Multiple military and civilian facilities reporting drone sightings, Polish railway tracks being sabotaged, Portugal and Spain losing electricity for multiple hours, Russian submarines and warships along the EU coasts, severing fiber connections between Sweden and central Europe, the list goes on and on.

Obviously infrastructure will be attacked and communication cannot depend on Starlink, services from US tech companies, nor be centralised.

So, which networks (from software to hardware), can citizens join to bolster their communication in case of war? Meshtastic? Meshcore? Jami? Briar? Freifunk? What exists? What can work? Which limitations are there?