CalyxOS development is paused right now but it's still available and campatible with more devices. I wouldn't recommend a currently unsupported OS but personally I'm still using it on my Pixel 7a. I had some google integration issues in GrapheneOS, plus I prefer the focus on privacy instead of security.
My main source regarding the privacy/security stuff is this blog (in German). To be clear, /e/ isn't bad on that front, the alternatives are just better.
You can read mode on the OpenAI integration in the /e/OS forums and the fairphone forums.
/e/OS is just another android rom, and unlike calyxOS or grapheneOS, /e/OS isn't very privacy focused. There's some weird stuff regarding a hidden "license id" and some of their services rely in openAI. You might as well just use a "real" privacy-first android rom if you're trying to get away from tech giants, their tracking and closed source software.