Chains are just functions (kind of a useless abstraction in my mind, hot take? πΆοΈ ). If you want to call an LLM or perform some function, you can just do that π Was there something specific you wanted to do? We have a few features similar to chains for specific functions (most commonly generating structured output)
Depends on what you mean by "custom LLM". If it's an OpenAI-equivilant API, it's pretty easy to change the base url to point to it. Otherwise, you can implement the CustomLLM class
https://docs.llamaindex.ai/en/stable/module_guides/models/llms/usage_custom.html#example-using-a-custom-llm-model-advanced