You can get a close enough view on this by finding a phone supported by LineageOS and installing it without anything esle (e.g. no fdroidPriviligedExtension, no

You can get a close enough view on this by finding a phone supported by LineageOS and installing it without anything esle (e.g. no fdroidPriviligedExtension, no openGapps etc). Alternatively, or maybe even better to what you ask, if you have a Pixel phone you can build RattlesnakeOS, again without adding anything like openGapps, which is almost pure AOSP iirc.