Raspberry Pi have an official AI HAT now, or try the NVIDIA Jetson, but they are mostly focused on local inference processing - stuff like pointing a camera at something and have it tell you what is - apple vs banana vs carrot type stuff. The Raspberry Pi AI HAT has some fun guides, is reasonably cheap and educational based.
If you want to get into LLM learning, OpenClaw is worth a look. Or if you don't mind the China issues, DeekSeek Ollama is very good at giving you details of it's though process and how it is working. You can play around with it, but it's quite technical depending on your background.
Generally though, the bit companies providing AI at the moment (Google, Meta, Anthropic) are spending billions, at a huge loss on massive AI systems. So, it's impossible to match what you can currently just hire from them. The assumption is once everyone is dependant on them and just a few companies dominate the market, the prices are going to ramp up to cover the losses - look at GitHub CoPilot and it's recent steep price increases.
If you really want an 'army to do your bidding' something like Claude Cowork is very (scarly) powerfull. It can take control of your PC and use programs installed on your PC, or install anything it thinks it needs or will help you with your day.