Except the native width of Tensor Cores are about 8-32 (depending on scalar type), whereas the width of TPUs is up to 256. The difference in scale is massive.
see this blog for a reference on Blackwell:
https://hazyresearch.stanford.edu/blog/2025-03-15-tk-blackwe...
If not, what's fundamentally difficult about doing 32 vs 256 here?