Palmolive
This isn't ChatGPT, but I did write a guide on how anyone can get Google's Gemini AI on their Pixel phone!
It works great! You can also get a 2 month free trial to try out their Gemini Advanced AI model, based on their largest, most complicated language model Gemini Ultra. Just disable Gemini Apps Activity to prevent your prompts and Gemini chats from being saved by Google.
It works very, very well! I have Gemini doing a weeks-long research project for me currently. I want to make a special build of GrapheneOS with charging control, adblock, and App Manager as a system app, with full app data backup without root. Complicated to say the least... Gemini has analysed thousands of files in GitHub databases for me, read countless scripts, and done so much research for me that it would have taken me over half a year to do on my own! I have to have Gemini Apps Activity on for this, but I'll just delete my data and turn it off after it's finally done.
Gemini Advanced is equivalent to ChatGPT 4, the pay for it version, but affordable and you have unlimited prompts. I've spent over 8 hours at a time with the AI working on this project, and I can say its bloody fantastic! You can set it as your assistant, or not and just go into the app to use it. Check out the linked guide!