Compared to Yuan, I think pushing BRICS currency is more reasonable and more accepted by more people. The reason is because BRICS currency also has the same goal of de-dollarization, backed by more countries, and, the framework is clearer. When China wants to push Yuan to be the same currency as USD or Euro, they need more than just economic stability, but also trust and transparency, which is still a challenge since Yuan is fully controlled by China Central Bank, and maybe only a few countries are interested in it and its usage is still limited. But maybe China with its overprotective policy towards its economy also does not want BRICS currency to be bigger than their own currency - it can be said that they are still hesitant in this matter and prefer to push their own currency.
I'm also thinking the same thing, their BRICS currency makes the most logical decision.
However, it shows that BRICS country aren't really solid, maybe each country just have their own interest and try to make their own currency ahead, trying another attempt of domination to compete with USD domination.
So far, nothing comes close to USD domination , even if BRICS released its currency I'm not so sure it will succeed.