Taking games designed for desktop GPUs and running them on mobile GPUs with tile-based-deferred-rendering hardware will be a disaster. Mobile GPU designs will choke on modern games as they're designed around hardware features that mobile GPUs either don't have, or that run very slowly.

Peak theoretical throughput for the GPUs you find in ARM SoCs is quite good compared to the power draw, but you will not get peak throughput for workloads designed for Nvidia and AMD GPUs.

You don't have to use tile-based rendering on these chips anymore. They can directly draw to the entire screen.

Isn't the GPU on Apple Silicon machines a tile-based "mobile" GPU design? Many of the hardware features that traditional GPU's have and mobile GPU's lack can be easily "faked" with GPU-side general compute.