I'll use this post as a shameless opportunity to tell more people about a little side project, I made:
http://languagemodelbuilder.com teaches you (in a few hours to days) how to build an LLM from scratch. It's entirely free, without accounts, and without data collection.
I wish this was available for young folk in Romania: As it happens: macOS: 2.70% of desktop operating-system usage in Romania; OS X: 2.55%; Combined Apple desktop share: approximately 5.25%; Windows: 90.65%; Linux: 4.02% or so AI tells me.
There are GitHub repos with the code from Sebastian Raschka's books, which build an LLM from scratch in PyTorch (some examples run fine even on CPU-only setups) using a GPT-2-like architecture, as well as his new book on reasoning models that came out recently.
[Off-topic] Your name sounds familiar...
http://languagemodelbuilder.com teaches you (in a few hours to days) how to build an LLM from scratch. It's entirely free, without accounts, and without data collection.