Was Zealandia above sea level during the last ice age? Like how Sahul or Sundaland were?
Was Zealandia above water during the last Ice age?
For the most part, no.
New Zealand's North and South Islands likely would have been connected, New Caledonia and other currently existing islands would have been larger, and some now-submerged areas would have been isolated islands that barely poked above the lower sea level at the time of peak glaciation. However, the vast majority of Zealandia is currently over a kilometer beneath the current sea level, which means that it was over 800 meters below sea level during the peak of the most recent glaciation.