In August 2024 I attended the He Kāinga Mokopuna Designs webinar and was really impressed with their project and their willingness to share the architectural designs they'd developed for affordable housing. 
The designs are available through their website and you can also watch the webinar and other clips. As they say on their website:

"Our research project stems from the pressing need for whānau in Tāmaki Makaurau to expand their living solutions as whānau grow and need more space. In today's economic climate, finding affordable and suitable housing has become increasingly challenging. This project explores innovative ways to create affordable, sustainable living solutions that respects cultural values and meets the expanding needs of whānau. By conducting in-depth cost analyses, streamlining council consent processes, and developing user-friendly resources, we aim to provide practical and effective solutions for our community."