Feijoas are commonly grown in NZ.
I love them, although some people find the perfumed fruit a bit intense.
They'll get pretty big, but respond well to heavy pruning and some cultivars are dwarf-ish.
They're not too fussy, but have shallow
roots, so you don't want to be digging around them.
They love sun, so the sunny edge of a food-forest, underplanted with the usual suspects like clovers, alliums and comfrey...
They're bird-pollinated. A good prune and plenty of mulch will bring them in.
Most cultivars aren't self-fertile, so keep that in mind.
I won't make any cultivar recommendations, since they'll be called something else, but I do suggest you get grafted, named cultivars: seedlings can take ages to fruit.