RISC-V is indeed what I thought, but hasn't MIPS also been free (enough) and open for at least a decade? You'd think that on licencing alone that'd be enough for a replacement in new products.

Edit: I am mistaken, it seems that though MIPS is used in all sorts of things that I'd expect wanted the cheapest possible CPU core it has only become free for academic use. I wonder how common that mis-conception is for those not active in the space?