In both Brazil and the US, making something like Pix mainstream requires regulation. Brazil did its part, but it’s unclear whether the US will do the same anytime soon, I don't think so, unfortunately. Technically, it would benefit the American population (the process of making pix payments is so smoothless), but payment companies may have little incentive to support it, and could lobby against it.

In Brazil, the Central Bank overpowered the coordination problem. In the US, it may be the opposite: the government seems to have less power over the payment lobby, or at least less willingness to confront it directly.