There aren't any good ways I know of for cryptocurrencies to remain useful without an electrical power grid, and the internet that makes possible. So, those aren't my focus, although nothing really is, TBQH.
Community is people. Start with the people around you, where you live now, and if, God forbid, there's a crisis or disaster, you'll already have a community around you. Usually our neighbors have very similar outlooks to ourselves, and commonalities that create numerous opportunities for mutual endeavors.
Seek to avoid controversy while remaining true to your principles, and you'll be amazed at who you can get along with. I have neighbors that abhor homosexuality, and neighbors that abhor homophobia. I can still build their decks, and they can still appreciate that service.
I live in an area with geological hazards, and should those arrive, it will be a catastrophe for me. It will be less of a catastrophe for we neighbors who already work together, as we will be able to work together then, too.
Einstein said something like 'I can't predict the weapons WWIII will be fought with, but WWIV will be fought with sticks and stones.' Nothing is guaranteed, but people need each other. Help them, help yourself.