Stablecoins are basically on-chain gift cards, with each token priced at about a dollar. Some (USDC, PAX, etc) have businesses you can directly redeem the stablecoins in order to get $1 sent to a bank account, and others (DAI, FRAX, UST) have more complex mechanisms to stay at or ~$1.

If you're using a chain that isn't BTC (technically you can use USDT on Omni but almost no one uses it for this), you can probably send the person a stablecoin that is priced at $1 USD.

And yes, people in Nigeria and other EMs do this every day, either for remittances, FX trading, or other reasons (reasons can be legal or illegal, i'm not supporting harm or illegal use cases but at some point we gotta recognize the 'freest' countries either still support race-based class discrimination or legalized slavery, so it's insufficient for the purposes of good faith discourse to throw pseudo mic drop rebuttals that assert legal institutions are infallible).

EDIT: and to pre-empt the "what if the stablecoin goes up to $2 or down to $0.50???" questions: - Centralized stablecoins like USDC, PAX, etc have licensed businesses that use actual banks to store the reserves, so if anyone wants to sell me their USDC for $0.75, please do and jog on - Decentralized stablecoins like DAI have more complex checks nad balances, and with those, unless you're a market maker or doing something that requires a non-top 3 decentralized stablecoin, it's often better to go with the ones that have been audited and/or battle tested, provided it suits your use case.