Here you can find a list but im not sure if it will help you , be careful not to brick it (i wouldnt recommend to flash anything), my laptop doesnt have UEFI on the dedicated NVIDIA GPU and it works with UEFI , as far as i know you dont need UEFI on the dedicated GPU.
Extensive repository of graphics card BIOS image files. Our database covers submissions categorized by GPU vendor, type, and board partner variant.
www.techpowerup.com
Edit: You should have UEFI enabled on your iGPU , select the iGPU in GPU-Z and you will see, it should look something like this: