Be aware that “everything” is probably untrue, though. Most of the custom ROMs still have a lot of Google stuff that is hard to replace / get rid of even with MicroG etc. (e. g. Captive Portal Check still phones home to Google servers on Calyx OS - if not deactivated in settings). Graphene (only on Pixel Phones 👌) probably comes closest. For detailed analysis check:
https://www.kuketz-blog.de/android-grapheneos-calyxos-und-co-unter-der-lupe-custom-roms-teil1/
You can, on certain devices, install /e/os/ and deGoogle everything.
There’s a new market for preinstalled devices popping up, too: https://cybernews.com/gadgets/murena-degoogled-pixel-tablet-launch
Be aware that “everything” is probably untrue, though. Most of the custom ROMs still have a lot of Google stuff that is hard to replace / get rid of even with MicroG etc. (e. g. Captive Portal Check still phones home to Google servers on Calyx OS - if not deactivated in settings). Graphene (only on Pixel Phones 👌) probably comes closest. For detailed analysis check: https://www.kuketz-blog.de/android-grapheneos-calyxos-und-co-unter-der-lupe-custom-roms-teil1/
(in German, use (Firefox?) translation if needed)