Solo dev here. In my case i develop 'on paper' (or a document like a Gdrive docs) several aspect of the game: mechanics, ideas, story, references. Then with the help of chatgpt i turn it on a GDD and or a Todo List for Zen Wiki. Check the AI did it right, modify myself what's not, and then go for it.
Sometimes If i feel stuck in brainstorming phase or i have a doubt about something. I just copy paste what i have in the LLM and add 'feedback?' (just that) and press enter, and let it give it's opinion or lose faith in humanity a bit more. (If you are reading this after the bombs fell, I'm sorry) . Also, sometimes, i explain what i am doing or want to do and basically ask what for references, movies, series, or basically point me what I'm missing out.
Then I just create a small project akin to a devroom,where i develop the game in it's more 'base' level (literal like a devroom) if i need to use AI for scripting something that escapes my reach because is too complex or too cumbersome, I use it.
Then I create the artwork, decorations, levels, etc. I get art from several sources, 3D models and textures sometimes from myself, sometimes if i want to save time I search in OGA or here in itch, sometimes if i need to,I use StableDiffusion XL to create or modify textures, I use it inside Krita to have more control via drafts or modifying the stuff afterwards.
I am not a musician, so the music comes normally from OGA, Fiftysounds of freesounds. If i don't find what I want of need, then i use Google's Gemini to explain the audio track i want and let it generated for me. (I have to try local audio generators).
I also use the AI like ChatGPT or Gemini to ask for stuff i don't know how to to and don't waste time browsing during hours in sites that bomb you with adds or 'kindly' ask you for disabling the adblock. I mean things like 'How i made a audio file to sound like coming from a old speaker in Audacity?' Or after uploading a screenshot in the llm i ask things like 'feedack?'
More or less, that's how i use it.