Thanks! For langchain you can repoint your base_url in the client. Autogpt I'm not as familiar with. Closed loop robotics using LLMs may be a stretch for now, especially since vision is a heavy component, but theoretically the patterns baked into small language models running on-device or hosted LLMs at higher level planning loops, could be emulated by a butter cache if observed in high enough volume.
For AutoGPT, there is the option to set a llamafile endpoint, which follows the Chat Completions API. So, theoretically, you should be able to use that to point to Butter's LLM proxy.