Part of why it happened for Apple's chips is that there weren't any Linux-compatible GPU drivers. It's easier to justify investing lots of time and effort into something like this if it makes hardware start working than if all it does is mean you're not using a proprietary driver and in the medium term likely have worse performance.

The open-source NVK driver in Mesa has gotten quite a lot of attention over the past couple years, unfortunately it will probably never be competitive with the proprietary driver on older hardware (Pascal (10xx series) and older) because those GPUs require a proprietary firmware blob in order to increase the GPU clock speeds.