World reserve currency was solved by Keynes and Joan Robinson in the 1940s. What you do is have a currency no country controls that acts purely for exchanging one national currency for another. Give it to the united nations or something.

If you take a national currency and make it a world reserve currency then the nation that does do has problems with balance of trade, deficits, and mathematically screws themselves over. This is because you currency becomes overvalued compared to those of over countries, meaning your domestic manufacturing has problems competing, among other things.

We already made the mistake of one national currency becoming the world currency post WW2. I hope its not a mistake the world chooses to repeat.

This is what cryptocurrencies do, but remove the need for an intermediary and codify the rules in software, so it is much harder (near impossible?) for politicians to manipulate the money supply.