If programming GPU drivers was not something only a handful of employees with NVIDIA or AMD badges could do (because of NDAs, non-public documentation and immense complexity), somebody would have tried.
Writing GPU drivers is not hard per se. It is impossible if you don't work at the vendor and have access to internal documentation.
Knowing how to write a kernel (which incidentally I am doing for the second time) doesn't mean you have years to dedicate to reverse engineer something as complicated as a GPU