It is being developed by OrdenKrieger and yes dev is still active on the rom, recent update was just 4 days ago.
currently its a mixed bag, they have got refresh rates and VoLTE and VoWIFI working on it alongside other features but some aspects such as Air Triggers are still being ported. SOC has improved dramatically also, I only get about 8 hours from a full charge.
It seems promising since Asus did give out the phone to devs etc. Maybe once its matured (only 6 months old) then it might be worth going over too.
I was curious to ask because A11 seems a miss from ASUS and I have a gut feeling it'll go the same way as ROG 1, one major update then a year of "no info yet" from mods only to be told a year later that there will not be another os update. Hence me seeing if anyone here has tried it out and see whats missing at the moment. But it does seem given time that Lineage will contain most if not all features from stock.