For the needs of "degoogled but fully functional Android OS" these days at the end of 2023, the options are LineageOS for most phones, GrapheneOS on a Pixel, and that's it? Or are there more projects at this point?

iodeOS, calyxOS, /e/OS are all good projects. divestOS are also good, but probably not usable for most, because of the lack of google play alternative.

paranoid android seems to still be a thing. The introduction on the website is sparse, and I havent tried it. So I cannot speak for how good it is.