As you mentioned, the project is not solely, or even primarily, for a Football Stadium.
The proposal calls for “expected to include retail, residential, commercial, hotels, hospitality, cultural and community facilities,”, the stadium being just one item.
It also, as proposed, calls for about $170 million in state money (with expectations that total state investment could end up at twice that amount) - the rest is a wild-*** guess as to how much private developers would end up putting into all the various stuff in the region they are hoping to see developed - hotels, apartment buildings, restaurants, entertainment venues, etc.
The Real Estate Project – New Aloha Stadium Entertainment District (NASED) (hawaii.gov)