Good point Owen
So...
I'm a bit surprised at the results tbf - I would have thought that oil filter would have been the clear winner (since Honda have used only 2 types of oil filter since 1980s up to present day!).
I think there might have been some skulduggery going on in the back ground... I did wonder whether I should post up the part numbers or not but decided to try the honesty of the forum members and go full geek by posting it (probably a mistake

)
Anyway, the answer is...
► Show Spoiler
Only the Air Filter is still available
Yes, I am really flabbergasted that the oil filter is different and that they can't supply one - that's the one thing I was sure they would still do and I did rather expect some of the brake stuff to still be available.
Sadly not, though
Nissan actually beat Honda in their parts supply for older vehicles - I can still get master cylinder overhaul kits for my Sunny B11, for example.