Please see my post above on why blockchain is useful in this one specific instance.
Rather than being reluctant, China is trialing this already via Project mBridge with central banks of Thailand, the United Arab Emirates, and Saudi Arabia. Another term for a multi-nation-backed blockchain system is a multiple central bank digital currency (CBDC) system, so that's basically what it is.
This is using some cryptocurrency - blockchain nonsense.
Only Russia is actively supporting it, with China neutral, South Africa reluctant, and Brazil and India not even participating.
This Ben Norton video is a long watch, but an excellent one if you want to understand what Russia and the rest of BRICS are trying to achieve and why.
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy:
I 99 percent of the time think that blockchain stuff is horseshit and unnecessary, but I admit this concept interests me.