Regarding your second one, I have some good news though: ASUS Zenfone 10 is smaller than iPhone 16 by 1.1mm x 3.5mm, Samsung S24 (base model) is 0.6mm x 1.0mm smaller, and Sony Xperia 5 V is only slightly bigger.
But the Sony suggested is slightly bigger than the iPhone 16 in 2/3 of the dimensions and this comment thread is lamenting how big the iPhone 16 is! I think people who see the iPhone 16 as so large it is not an option are unlikely to consider switching to Android for an even larger phone.
It's a shame, because Sony used to make smaller phones with only slightly lower specs than their flagship phones. I also still associate them with making sensibly-sized alternatives, even though they don't anymore.
There really isn't anything mainstream out there at all. Why? Majority, clear majority, of people rejected smaller size phones sadly.