I think XMPP would be the most appropriate tech for us to adopt, since it’s easily self-hostable, has great mobile apps, is federated, and doesn’t require an always connected bot to record chat history to know what was said while you were away. It’s functionally an improved IRC.
Python Crash Course by Eric Matthes is a supremely good book to start with for an absolute beginner, and I would recommend it over Automate the boring stuff (that would be a great followup though!).
It assumes absolutely no prior knowledge, explains concepts extremely clearly, never presents too much to overwhelm and frustrate beginners, and includes a good range of projects that should interest any perspective programmer.