I strongly disagree with the square aspect ratio being an issue at all for foldables.
What exactly you don’t find “pleasant or useful” about it.
For video it’s handy to not have hands securely on device without inadvertently impacting or obscuring playback and viewing the content.
Readability and UI elements aren’t negatively impacted either and only enhanced with my experience with Android foldables compared to my iPhone 16 Pro Max
It just doesn’t feel right and most apps and content are not designed for square displays. It’s too awkward an aspect ratio. Content mostly ends up stretching to fill the horizontal space and most of the time it simply doesn’t work: portrait images don’t fit in the viewport, the margins for text are off because websites assume you’re still on mobile (so you have to scan your eyes to the left and right too much), etc.
When new horizontal space is introduced content has to decide whether it wants to stretch to fill the width which makes media browsing and text reading worse (most apps on android in my experience go this route) or introduce margins to maintain a portrait aspect ratio in the main view (a timeline, text, traditional UI, etc.) which introduces an awkward negative space.
I’m not sure I can describe it well, all I can really tell you is that most experiences I had on android in unfolded mode felt unoptimized and worse than the folded UX outside of some limited use cases like viewing images, some videos, and the Google Maps app which feels great. I had the opposite experience than you did apparently.
Maybe Apple can pull it off with their different approach to the hardware (aspect ratios) and better software support.