fast.ai has a course on building Stable Diffusion: https://course.fast.ai/Lessons/part2.html
...sigh...
Yes, they tell you do their first course but I have no confidence that one course in this stuff will make me "comfortable with building an SGD training loop from scratch in Python, being competitive in Kaggle competitions, using modern NLP and computer vision algorithms for practical problems, and working with PyTorch and fastai"