Been looking for a lightweight 15.6" laptop for my future TAFE course a while now and this just happened to have $320 off as part of HN's 20% off Acer laptop sale. Not the best in terms of specs, but for a big screen featherweight, it's the lightest (0.99kg) in this part of the world.
RAM can be upgraded in the future as confirmed by Harvey Norman.
Pretty good if you need the lightweight. I bought a Lenovo Thinkpad E590 i7 8th Gen 8GB RAM, 256GB NVME, RX550, 15.6" FHD for $1169. Expandable to 32gb RAM and a spare sata port for a 2.5" drive. Down side is, I have to wait 3-4 weeks for delivery.