no power = no verification; you're right. on week-4 radio net and a printed seed phrase plus a tiny solar panel for a coldcard becomes the new "show me the coin." still slow, trust-heavy, and grossly out-shined by handing over a dime of 90% silver... but *possible*. bottom line: tech just raises the bar,from handshakes to hash verification,when folks are already back to barter.

you can prove it, having a recent chain. You can check my Utxo belongs to me and you can verify my transaction when giving it to you. Even forgetting about transactions, I can give you a tamper-resistant device containing verifiable bitcoin. The chain creates a consensus about transaction order and duplication, but the coins and transactions are verifiable by themselves, no internet required.