The late 18th/early 19th century saw rapid growth in the Maori population thanks to the introduction of the potato, as well as massive warfare caused by this and made worse by the introduction of firearms. Many people were displaced.
A group of Maori in this period infamously attacked a European ship and got transport to the Chatham Islands, where they eventually killed and enslaved the native peoples and effectively acted as a colonial power. What I'm interested in is what if groups of Maori attempted to settle on Tasmania in a way similar to the Chatham Islands (with or without the genocide and slavery, but that's probably inevitable)?
The biggest problem is there's a very small window of time for this to happen before European control is complete (no later than 1820 OTL), but if you gave the Maori the potato maybe a decade or two earlier and delayed/slowed down the European settlement of Tasmania a decade or so, what might happen? Could the Maori ever establish themselves as a significant minority group in Tasmania? How might their relations with the British be? Would they get their own version of the Treaty of Waitangi or might the Tasmanian government treat them substantially harsher than New Zealand ever treated the Maori?