BRICS is rather interesting because it appears to be heading down the path of the self-fulfilling prophecy. In practice, it’s little more than a flashy name and a social club for government leaders to meet at all those annual conferences, with little tangible impact to show for it. Contradictorily, however, this lack of concrete action seemingly has allowed people to project onto BRICS whatever they want it to be, actually further contributing to its inflated sense of significance.
One remarkable thing that comes out of this phenomenon is that, due to the presence of China and Russia in the group, the West, as an outsider looking in, is unable to resist framing the group's actions through its Sinophobic and Russophobic perceptions. This means that the other countries are lumped together with China and Russia by association through the West's paranoia. Countries that had no interest at all in really siding with China and Russia in any major respects against the West, like Brazil, South Africa and even India, suddenly found themselves non-consensually grouped together with them by the West itself whenever it makes those "G7 vs BRICS" narrative comparisons, or frames BRICS as a "anti-Western bloc."
The self-promotion of BRICS by its member countries, I would say in part by their governments as a way to elevate their countries to the stature of China and Russia on the world stage, has lend it a particular exaggerated and overblown common perception in those countries for nationalistic reasonings. To give one superficial example, I've surprisingly frequently encountered Indian news coverage of the grouping use that "BRICS" logo where each letter has that country's flag, meaning that the Indian flag "I" is right in the middle, which I suspect is the reason why they use it. All this is meant to say that all the hype around BRICS, despite being frankly all talk and little action, has created a decent level of nationalistic pride from a large amount of the populations of the member countries. Therefore, whenever Western media blow up BRICS as some boogeyman against the West or when politicians like Trump openly threaten to tariff the group if they threaten US dollar hegemony, it actually can elicit a sense of indignation from those member countries.
In truth, whenever the West talks about BRICS, they're really often just talking about China and Russia, yet through this, the entire group gets painted with the same brush. This casts BRICS as more consequential than it is, and in a curious twist, it even fosters a certain solidarity among the countries in the group, including those like Brazil or South Africa that might not have otherwise seen much common ground with China and Russia. Those countries are not necessarily opposed to the West, but have a certain sense of high national pride - as the leading developing countries of the Global South - that gets hit as collateral damage whenever the West simple-mindedly attacks BRICS as a means to just attack China or Russia. This mirrors the history of previous 20th century Global South groupings like the NAM following Bandung, where the external reactions in lumping the group as some credible unit helped it bond together more than any internal actions did.
Through BRICS, China, for its part, also has gained a form of soft power connection with countries that have little historical or cultural connection to it, such as Brazil and South Africa. For example, consequentially, it's also provided the announcement stage for the recent attempt at Sino-Indian detente, which I doubt is a mere coincidence as such a move could be justified domestically by Modi through the BRICS mechanism as "being the bigger person for the sake of the group" and "to give Russia face as the host" in a way that ultranationalist sentiment in India might have been outraged by if conducted in a strictly bilateral context.
Through this, I'd say the foremost factor behind the development of the grouping in any relevant measures will not be primarily any internal dynamics but the external response from the West. In short, if the grouping actually ever gets anywhere materially, it will be principally because the West is effectively helping to create the very thing in actuality it views BRICS to be in its imagination.
