Sorry, there is no way to open them with GPU.
With GPU Coder™, you can speed up the execution of Simulink® models that contain MATLAB Function (Simulink) blocks. GPU-accelerated simulation also works with models that contain blocks from the Deep Neural Networks library of the Deep Learning Toolbox™ or the Analysis and Enhancement library from the Computer Vision Toolbox™. GPU-accelerated simulation requires a CUDA®-enabled NVIDIA® GPU.
So you can speed up the execution of MATLAB Function Blocks... but not the opening of models.