> Can someone explain simply where does MLIR fit into all of this?

It doesn't.

MLIR is a design for a family of intermediate languages (called 'dialects') that allow you to progressively lower high-level languages into low-level code.

The ML media cycle is so unhinged that I've seen people simply assume out of hand that MLIR stands for Machine Learning Intermediate Representation.

> Side-note: Mojo has been designed by the creator of LLVM and MLIR to prioritize and optimize vector hardware use, as a language that is similar to Python (and somewhat syntax compatible).

Are people getting paid to repeat this ad nauseum?

MLIR includes a "linalg" dialect that contains common operations. You can see those here: https://mlir.llvm.org/docs/Dialects/Linalg/

This post is rather unrelated. The linalg dialect can be lowered to LLVM IR, SPIR-V, or you could write your own pass to lower it to e.g. your custom chip.