From my experience

- regional flights (apart from Japan) do not have a proactive nut service
- Japan, there's the Japanese rice crackers (otsumami)
- for longhaul, nuts are offered proactively

Interestingly for the Japan flights, there used to be otsumami on the return flight from Japan to HK but not on the outbound (where they served nuts). Now there's otsumami for both legs.