Has anyone had any success earning tier points/avios when flying Fiji Airways with an AA flight number? I'm leaning towards nothing will be awarded but it's much cheaper cash wise flying AA/FJ via LA than flying with BA/FJ via SIN or HKG.

Award availability for domestic flights in Fiji via avios is really good. The BA avios search engine doesn't recognise many of the airports in Fiji so you have to manually type in the destination and play around with the iata code a bit but aside from that, quite easy to book.