Only one was photographed, but it seemed to be a pair. Birdlife has suggested escapees. There isn't very much in way of people around the block though, and I saw them over about a month. They did seem settled in, and I'm wondering if they were wild, border breaking budgies. Will see if they return this year for Spring. The area has nice open native grassland, on which to feed.
There is a reasonable chance they were wild birds, if they were behaving wildly. Many small flocks, pairs and singles were seen around Canberra in 2020/21 Summer, which is well outside their typical range. They were wild birds.