My first Android phone was a Samsung Galaxy S2. It weighted two grams less than that Hiby R1. Of course it was much larger, but tiny by today's standards.
Now that I think about it, going no-buttons might have been a driver towards larger screens. Having at least a few buttons seemed to make it much less necessary.
https://m.gsmarena.com/samsung_i9100_galaxy_s_ii-3621.php