There are a few places around NZ who already relied heavily in the domestic market, Bay of Plenty, Taupo, and Hawkes Bay to name a few so you are already in a good place from that perspective. I presume you know your local RTO well and have reached out to Hamish Saxton and newly appointed Heather Mathews at Hawkes Bay Tourism to see what their plans are for a domestic tourism promotion?
Whilst I am not an expert on social media marketing I would also suggest that a targeted social media campaign on Facebook etc into Wellington, Tauranga, Taupo, and Auckland would be a cost effective to get in front of a domestic audience with some great value deals, possible packaged with other partners. Think weekend escapes etc..
You might want to also join this tourism industry Facebook group if you haven’t already https://www.facebook.com/groups/647725352678015/?ref=bookmarks
This article may also be of interest, tour operators using their vehicles to distribute food and medical supplies in local regions. https://www.tourismticker.com/2020/04/16/ito-headfirst-travel-pivots-to-delivery-services/
Best of luck, Jason