Something like LightningPiggy (https://www.lightningpiggy.com/ ), but with Cashu and maybe some more interesting interface?

NFC, USB text files (probably more difficult) or something similar.

A way where you have a feed that you are feeding it Bitcoin, not sending to it.

ESP32 cashu client should be easy (micropython?) enough to vibe-code :)

Or even more fun - if locked to pubkey (forever), it could be completely offline. Just verifies signatures of paired mint and shows that the keys are locked to pubkey.

And then there's a button to dump all tokens for exchange.