Long time answering...

Yes mangoe fruit ok in NZ. The problem is getting the right cv. for our climate. I understand there was a DSIR trial orchard in S Ak somewhere in the 70's that had about 20 cv.s fruitng to commercial quality, but they were all destroyed after a disease outbreak. Which is why Mangifera indica is on the NZ potential commercial fruit list, and why it is now so hard to import material for a new run of trials.

It is technically illegal to grow seeds from imported fruit, as the regulations are different for fruit import for eating, compared to seed for sowing. If however you find 'Kensington Pride' or 'Bowen' (same plant different name) mangos in the shops, and if by chance a seedling germinates in your compost heap, then you will probably have good luck with, provided you protect the flowers from rain in the srping. This cv. fruits way south of Sydney in Aussie (although comercially its southern end is in northern NSW), and grows true from seed.