If it's anything like the M1 Max and M1 Pro, the real-world GPU performance doesn't quite extrapolate the same way as the synthetic benchmarks.
From what I've gathered, the performance per watt of the M1 GPU isn't actually that much different than nVidia's 3000-series performance per watt in real-world applications. I'd love to be wrong and discover that Apple has also cracked the code on making GPUs more efficient than established industry players, but I think it's not leaps and bounds better like they've claimed. At least not in real-world applications.
Also, while the 3090 is $3000 because of shitcoin miners and scalpers profiting of the demand, the MSRP is half that (and you can still get it at this price provided a bit of patience, which, admittedly, sucks to have to do).
I can’t find ‘em for under $750.