The one you linked to is based on Karpathy's tutorial: https://www.youtube.com/watch?v=kCc8FmEb1nY, except changing to train on tinystories in stead of Shakespeare. smolGPT also looks inspired by nanoGPT, also from Karpathy: https://github.com/karpathy/nanoGPT/blob/master/train.py

The implementations are different, so I don't think you can consider it a rip-off.