A summer sleeping bag must be only rectangular and synthetic fill. Rectangular shape provides much more space than mummy and you can use it as a quilt after all.
Synthetic fill is much more cheaper than down while down has better warmth-to-weight ratio. However, you don’t need lower comfort temp rating for a summer sleeping bag.
I’d suggest Naturehike LW 180 it’s budget friendly and very compressible.
It’s no the most ultralight in the list but that high-end models like WM Summerlite cost about $200-400