That sounds interesting; what do you mean by "in a heap"? Is the stack they're currently linearized into not GPU-friendly? I don't know much about GPU programming, so this might be a dumb question.
My idea was to make a Vec of nodes with pointers to indexes in the vec, so it would be easier to send this array into the gpu. I wanted to make a minimal version example of making a micrograd network run on the gpu, with wgpu or macroquad, but I didn’t complete it, so would be nice if someone else did it. :)