It means you'd have to issue local currency against local infrastructure. Or otherwise anything local. I guess that doesn't make much sense either.

You have to GIVE a currency value. What that means is that you must give people a reason to use that currency. Now internally in a country this is done through taxes and the bank system. Externally however this has to be done differently. It must be "guaranteed" to be exchangeable ... to the global reserve currency (so that anyone can buy what they want with it). How do you guarantee that exchange rate ? By having an instrument that's guaranteed to be exchangeable for the reserve currency. A lot of US treasuries, a little gold, a little EU sovereign bonds, ...

So instead you'd have to issue currency and make it exchangeable for local assets. So you'd loan that to local people to build roads, harbors, bridges, buildings, ... That doesn't work, because sovereignty means that you can't exchange those things for the global reserve currency anywhere near as well as you can US treasuries. Because investors are acutely aware that the government could just immediately impound their money (and there's lot of historical precedent of that actually happening), whether it's local currency or local assets. Investors would have to accept that they can bring money in, but not take it out. And good luck with that one.