Their comparison charts showed the performance of mobile GPUs, not the desktop ones. So, I wouldn’t call this “practical”. Most likely depends on what kind of models you are building and what software you use and how optimized it is for M1.

It will be definitely handy for finetuning large models due to huge ram, but in training from scratch 3090 is certainly better. They are seemingly cooking 128 core GPU, if they release this kraken it will beat 3090 in pretty much everything.