Interested on whether the /e/ project already addressed or have it on their to-do list the degoogling of the following:
Webview. Lineage OS uses AOSP Webview, but there is also the Bromite System Webview, which is actually degoogled.
A-GPS. Lineage OS by default uses Google for their A-GPS SUPL servers (supl.google.com).
DNS. Probably a non-issue with ROMS based on Android 9, but anything before that defaults to Google 188.8.131.52
Captive portal. Default checks go to connectivitycheck.gstatic.com.
There are probably other components of the ROM that might need degoogling, but this seem to be the big ones for now.