Personally, I dream of an open-hardware, FLOSS wallet, also usable on POS like a bank smart card, confirming crypto transactions like legacy/traditional ones on its own display.
Internally, the signature part isolated like a smart-card, "embedded signature" hardware as a measure against double (multiple) spending, and reasonable limits on offline transactions with both parties offline (e.g., €10k/month).
The "embedded signature" hardware part is a bit vague because technologically it's not clear how to do something like that in a "secure enough" way, but it's a necessary part and the limit somewhat lowers the risk.
For use: mounted as a smartwatch or a pendant with a retractable lanyard, like ski-pass holders.
Internally, the signature part isolated like a smart-card, "embedded signature" hardware as a measure against double (multiple) spending, and reasonable limits on offline transactions with both parties offline (e.g., €10k/month).
The "embedded signature" hardware part is a bit vague because technologically it's not clear how to do something like that in a "secure enough" way, but it's a necessary part and the limit somewhat lowers the risk.
For use: mounted as a smartwatch or a pendant with a retractable lanyard, like ski-pass holders.