I was out in the backyard and some onions have gone to seed, the flowers are attracting native bees. I'm not sure what type as there are many different native bees. They are only small, maybe 3 or 4mm long.
Yes the last ones, with the flattened abdomen and big eyes, are definitely hoverflies.
I remember very tiny bees from my time in Arabia, on the West coast of the UAE. They weren’t black, though. I suppose there must be hundreds of species of bees.