Sorry not to be able to give a clear answer here. In the present circumstances, it's difficult to say what visa processing will go faster, particularly as you're overseas. I expect you've seen this page.
https://www.immigration.govt.nz/new-...sa-application There have been stories on the threads since some of the INZ offices opened after the first lockdown which showed an amazingly fast turnaround on some cases, when people were resigned to waiting for months - it appears that it's a bit of a lottery.
The route you suggest is certainly a possibility. On the other hand, you may want to consider one advantage of applying for Partner of a New Zealander Residence while overseas is that you can be issued with Permanent Residence, given that you've been living with your NZ partner abroad for more than five years. F2.5.1 here.
https://www.immigration.govt.nz/opsmanual/#46503.htm (That is, you wouldn't have to apply separately and pay a fee for your PR when once you've been living in NZ for two years after getting your residence visa.)