Probably not, but it does mention a more general CUDA based solution that might be interesting to add to Pictrs. I could for example move my Pictrs instance onto a server that does have an older Nvidia GPU to accelerate stuff (to use for Libretranslate and some other less demanding ML stuff).
Edit: Ok looks like the resizing is anyways only supported on Pictrs 0.4.x which most Lemmy instances are not using yet. However this seems to use regular ImageMagick in the background, so chances are quite high that it can be made to work with OpenCL: https://imagemagick.org/script/opencl.php