I assume the hardware providers don't do this out of the kindness of their hearts. Do they get a % of tx fees somehow?

since 2 years, they have been modeling their own FPGA-version of Plonk on our library. As soon as I heard about them, I reached out and they were absolutely thrilled to be talking to us. We are discussing a mutually beneficial partnership at this stage. HW acceleration is not a priority for us yet, so it is nice to be able to shape up our collaboration in a deliberate fashion