Here is what I've come up with. The QF codeshares cover most independent airlines that fly from Australia to the Pacific.
HA Pacific intl destinations (From HNL)
Pago Pago, American Samoa (PPG)
Papeete, FP (PPT)
Guam, USA (GUM)
VA Pacific intl destinations (from Australia)
Apia, Samoa (APW)
Honiara, Solomon Islands (HIR)
Nadi, Fiji (NAN)
Nuku'alofa, Tonga (TBU)
Port Vila, Vanuatu (VLI)
QF Pacific intl destinations (from Australia), incl codeshares
Espiritu Santo, Vanuatu (SON)
Port Vila, Vanuatu (VLI)
Honiara, Solomon Islands (HIR)
Nadi, Fiji (NAN)
Suva, Fiji (SUV)
Noumea, New Caledonia (NOU)
FJ intl destinations (from NAN)
Kiribati (TRW and CXI)
Apia, Samoa (APW)
Honiara, Solomon Islands (HIR)
Nuku'alofa, Tonga (TBU)
Neiafu, Tonga (VAV)
Funafuti, Tuvalu (FUN)
Port Vila, Vanuatu (VLI)
Honolulu, USA (HNL)
FJ intl destinations (from HNL)
Kiritimati, Kiribati (CXI)
Apia, Samoa (APW)
Nadi, Fiji (NAN)
Solomon Airlines (IE) intl destinations (from HIR)
Nadi, Fiji (NAN)
Port Vila, Vanuatu (VLI)
Tarawa, Kiribati (TRW)
I see a few options:
VA to APW, FJ APW-HNL. The only one-stop option from Australia besides NAN
VA to APW, ferry or short flight to PPG, PPG-HNL on Hawaiian. This is a standout because it is two island nations but a short trip between them, with no backtracking.
VA/QF to VLI, then VLI-NAN-HNL on FJ.
VA to TBU, then TBU-NAN-HNL on FJ.
Any airline to NAN, NAN-CXI-HNL on FJ.
Any airline to HIR, then HIR-NAN-HNL on FJ.
FJ makes a lot of things possible if you want to connect in NAN, but I am leaning towards to double APW/PPG option. Not all these flights are daily, in fact most probably aren't, so from here on it becomes about price and logistics.
