Can I acknowledge you are doing an amazing thing supporting your whanau to be the best they can be. I agree there are some funders who will fund small community based initiatives that are not registered charities. The website https://generosity.org.nz/ is a database of potential sources of funding. My sense is you would be eligible for COGs funding as they often fund projects that are grassroots such as yours. https://www.communitymatters.govt.nz/community-organisations-grants-scheme/

I have worked with groups doing mahi such as yours who ask one of their more computer literate community members to set up a give a little page where people can donate. Getting people to sponsor individuals and whanau who participate in hikoi could be a feasible option. check out https://givealittle.co.nz/. These folk may be able to help you as well: https://foundation.vodafone.co.nz/

If you do decide you want to register to be a charity your local community law office will be able to give you some advice.

All the best
Sandy