Square because trackpads have always been that way my dude and can be set to a ratio similar to common screen sizes.
Not awkward at all seeing how we hold smartphones these days and the onscreen keyboards are typically in the same location our thumbs need to reach when using both smartphones and the deck trackpads.
Sure you can argue size is small but most likely the deck internals won’t allow for larger size.
I liked/like the steam controller. I’ve got four. But the steam deck trackpads have been far and above more responsive for me.
Ammonia is specifically used for cleaning fine jewelry like gold. It’s in a lot of jewelry cleaner products. So maybe the ammonia isn’t good for the machine? Idk. Or it’s just another legal thing to cover some butts.