I don’t know about 15.1 but on 14.1 you can just grab UNLP backends and Aurora Store from the other included non-material design play store or F-Droid. AFAIK its all this there after 15.1 upgrade. I do get Play Store errors sometimes (since a few months) and still do on 15.1 it seems but that’s about it. The rest all works (on 14.1; not tested 15.1 well enough to say). I’m not sure what I’m missing out on. Google Sync adapters, for example, no idea what that. I don’t want to sync anything with Google. I use DAVDroid instead, and am trying to migrate as much as I can away from Google and other proprietary cloud services and as much as I can from the GPS. If something’s available from F-Droid, I try to use that instead, as long as it doesn’t lag (too much) behind GPS. Clearly failing in some regards (using Netflix and my bank app are both proprietary and Nova Launcher is proprietary as well etc) and sometimes I need root which isn’t cool.
PS: And yeah I’m using the official version from lineage.microg.org, whatever it is called.