[lxgr]

A currency being legal tender presumably has little bearing on whether the U.S. would consider it a currency. Some countries don‘t even have the concept of legal tender, while others recognize currencies they don’t issue themselves.

Being issued by a sovereign state would probably be a better test.

[kyboren]

> Being issued by a sovereign state would probably be a better test.

Aha, so they just need another layer of indirection.

Acting on the imprimatur of the country's central bank, programmatically issue a sovereign CBDC upon the deposit of BTC. Keep cryptographic proof of 100% BTC reserves at all times to provide ultimate credibility for your (potentially parallel) currency (so you can keep using dollars or pesos or whatever in your real economy). Allow intra-CBDC transfers for 0.1% fee and programmatic redemptions for BTC for 0.2%. Profit.

`ping -i1 www.bcr.gob.sv`...

[Xorakios]

The economic definition of "legal tender" is sometimes obscured in casual conversation.

It isn't "issued by a sovereign state" - that's "fiat" but rather "used for paying taxes." And sometimes, like in the US, debts ("all debts foreign and domestic").

Certainly it has to vary among countries of which I am ignorant, but generally in the Anglosphere it is debts, not payments, that trigger the definition of "legal tender."