Do you need a Threadripper to compete with M1 Ultra? Ryzen 9 7950X seems pretty comparable and doesn't require a 1000W PSU unless you must pair it with a 4090 or something.
Depends, how cache friendly is your workload? The M1 ultra has more than 4x the memory bandwidth of the threadripper. Of course the GPU makes a big difference in cost and power use. If you need a 4090, there's nothing comparable. But if the Apple iGPU is enough you save a ton of power and space.