Pen.el now can take advantage of GPT-J-6B via AIX. That means there is a completely free (libre) alternative to VSCode and Copilot.

https://www.reddit.com/r/emacs/comments/owwcwv/gptj_support_...

Get yourself a key if you'd like to try it out.

https://apps.aixsolutionsgroup.com/

You may make composite 'prompt functions' that combine both language models, and also fine-tuned OpenAI models and use them to extend emacs in all directions!