AusBonsai

My money is on Blueberry ash as well. The curving tip is very reminiscent.

We do have an eleocarpus in the garden. I will compare leaves tomorrow but these seem thicker and more leathery and I'm not sure that eleaocarpus would survive in that location without added water.

+1 for Blueberry Ash. I have one with very similar leaves. They grow large without extra water in gardens around here.

I checked the leaves on our eleocarpus today. It's leaves are almost smooth around the margins - just very faintly toothed where this one has really pronounced serrations around every leaf so I am still not convinced

My first though was blueberry ash. leaves look the same as a wild plant here as well as a nursery plant I have. Definitely would be able to survive a dry site, they pop up here in the drier spots.

This is the one I have. Elaeocarpus reticulatus "Prima Donna"

Looks very similar....

I'm amazed that even your self seeded trees seem to have great nebari

I would not count that as good nebari. Nebari is more than a couple of thick roots sticking out from the base. It does have good trunk flare. I'd put that down to the 2 quite large trunks that broke off. You can see part of the wound in the second last photo but I purposely took photos that would not show the damage
You should also note the amount of vertical roots removed from this tree to create a flat base. I do that to most of the trees I collect. I have no idea how this one will tolerate root removal but as mentioned it is of very little consequence if it fails so why not go hard and see what happens.