There unfortunately is no such thing as stock Android… the closest that exists is the Android Open Source Project (AOSP) which is generally considered too bare-

There unfortunately is no such thing as stock Android… the closest that exists is the Android Open Source Project (AOSP) which is generally considered too bare-bones to be usable on its own and is missing a lot of the things that Android users might expect. While there are third party Android distros based on AOSP available, they typically only support devices that are a couple gens behind or older, which means they’re not usually an option for anybody buying a current gen device. I wish Android were more like Windows or Linux where the hardware is somewhat standardized, the OS is the same no matter what it’s installed on, and you could just wipe+reinstall “plain” Android like one does with a PC with Windows to clear away crapware, but that’s not what we got.