just tried LineageOS 15.1 on my FP2 again. Installation (“dirty flash”) worked flawlessly, besides the fact that many, many tiny little features are gone
But I do have a big issue with the Netguard (Pro) firewall, as it blocks all traffic. I read/followed this FAQ entry tried turning it off/on again, even reinstalling it.
(Reinstalling is tricky though, as Android 8 Oreo seems to present a changed the device ID and presents individual device IDs to the installed apps requesting it. I think Netguard uses the device ID to compute the required key to unlock the pro features.)
That XDA thread would be my last resort… Maybe one of you folks here has an idea?