the role of monarch is not hereditary: The successor is determined by tribal representatives from across the nation.
The ceremonies took place in Tūrangawaewae Marae on the North Island, which is the seat of the Maori King movement.
The political institution developed in the 1850s, when Maori tribes decided to unify under a single sovereign in the face of an influx of British settlers and demand for their land, as well as broader political marginalization.
Today the role of the Maori monarch is largely symbolic. As a former British colony and current member of the British Commonwealth, New Zealand’s official monarch is King Charles.
So I don’t think this is monarchy in the way that you are thinking. The “Maori Monarch” is more of a political leader than anything, so in a US context, it’s kind of like the NAACP selecting a new president.