> “no private entity can claim monetary power, which is inherent to the sovereignty of nations” What a bizarre statement. Providing for security is also inherent to sovereignty of nations, but private security firms flourish. It's also odd in the context of Germany in particular where a private currency has been used for many years: https://en.wikipedia.org/wiki/Chiemgauer I suspect there's a lot more behind this sta…
Your German example is a bit silly to use here given that its exchange rate is 1:1 with euros. There are other regional currencies in other countries, they don't usually operate independently from the country's own currency though.
The Libra proposal kept its value constant with respect to a basket of currencies.