I suspect certain games, like Ingress, or GPU-intensive games, routinely max out phones' computing hardware. Chances are that badly overheating models are reasonably few and already known by gamers.
My experience with Ingress back in the day bears this out. That game would cause certain phones to reboot due to overheating, and others to throttle down so low they were worthless for playing.
Yeah except you're not going to reverse engineer the GPUs of a dozen SoCs just to save a few dollars on a beowulf cluster. Even in the best case you will reverse engineer one commonly used GPU and then pick phones based on that.