Seconding this recommendation! I've never been a super advanced vim user, but Evil is the best and most complete vim emulator I've ever used, and I try them on every editor or IDE I ever run.
Seems some of these are for Vim too, but I haven’t tried them yet:
https://github.com/jkitching/awesome-vim-llm-plugins
Scanning the list quickly, dense-analysis/neural perhaps sticks out since it’s written by the author of ALE, which is a very high-quality plugin.
Another option that is perhaps more the Unix way, is to run an LLM client in a terminal split (there are lots of CLI clients), and then use vim-slime to send code and text to that split.
Personally I’m still using ChatGPT in the browser and mobile app. Would love to try something else, but the OpenAI API key seems to cost extra, and something like llama probably takes time to setup right.
Been searching and have found some but nothing stands out yet.