I said “mostly” useless on its own. I believe Lineage and co have to supply their own replacements for some important features, and/or use the proprietary Goog

I said “mostly” useless on its own. I believe Lineage and co have to supply their own replacements for some important features, and/or use the proprietary Google Play Services. AOSP isn't a usable base product, like Chromium for example. (That's my understanding anyway. It's quite possible I'm wrong!)