~snip~
If a wallet allows the use of fiat or bitcoin, how does that resolve the issue that bitcoin is, at least currently, far more volatile that fiat currently? At least where I am in the U.S.
And how does a wallet provide the use of fiat currency? What is the path/method by which I take some fiat currency somewhere and get control over it via my off-line wallet?
What I meant is that in some wallets you can set the amount of the transfer in fiat, say $5, and the wallet will calculate immediately the amount of Bitcoin, based on the current exchange rate. Sometimes you'll pay a bit more btc other times a bit less btc for the same $5. This would be a bit similar as to using foreign currency.
Some wallets do offer some kind of exchange between fiat and bitcoin, such as Strike, or Chivo, etc. At the end of the day those are exchanges.