From the look of the branchlets, this is probably a young Allocasuarina littoralis (hairs obvious in the furrows, longish acute, erect teeth). A. diminuta is also in the area but usually has no visible hairs in the furrows and the teeth are rather broadly acute and spreading towards the apex. And A. distyla branchlets are more robust than these with a yellowish 'stripe' down the middle of the branchlet articles. See https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Allocasuarina~littoralis