fast.ai has both - the "part 1" section is top-down, and the "part 2" section is bottom up. You can do part 2 without having done part 1. Part 2 starts with implementing matrix multiplication from scratch, then backprop from scratch, then SGD from scratch, etc.

There will be a new version of the part 2 course out in a few weeks. It even covers stuff like random number generation from scratch, convolutions from scratch, etc. It gradually works all the way up to Stable Diffusion.

@karpathy's and the fast.ai lessons work well together. They cover similar topics from different angles.

(I'm the primary creator of the fast.ai courses.)