

Hey there, for starters A-GPS, stun, secure DNS, and several other preconfigured servers default to Google. Some of these can be changed with ADB. Check out a guide on de-googleing LineageOS for a more complete list. It’s not AOSP, but close enough. There are also Google servers configured in the sources. How valuable those connections are, depends on your threat-model. If you’d like a paranoid GSI, check out LeOS. It’s probably the most complete treble-compatible option. AOSP by default, isn’t very private.
LeOS isn’t very popular, because it’s a passion-project by one guy, with little marketing. Said guy is a somewhat opinionated Woodstock-era hippie, hence the colorful icons (they can be easily swapped via an icon-pack of your choice.) Though he is a friendly person.
To my knowledge it’s the only Treble-option with a hard stance on de-googling. Specifically made as an answer to some policies in eOS. There is an interview with him floating about, if you want the backstory. https://nixfaq.org/2021/01/exclusive-interview-with-guntram-lead-developer-of-a-popular-custom-degoogled-android-rom-called-leos.html