Im quite surprised by this, isn’t Parliament a crown/british concept?
I wouldn't think of it like that. Virtually every modern government has a parliament of some sort.
According to the RNZ Aotearoa History Show, Māori chiefs thought this separation was how co-governance would work when the signed the Treaty. There would be a Queen figurehead above, then the British would have a Premier and Māori would have an equivalent at the same level (not necessarily a parliament at the time, but it makes sense in a modern context). I'm not sure how accurate that is, but this news doesn't surprise me.
But I also noticed the article covers nothing about how it might work in practice. It seems like a different form of protest rather than a serious bid.