Wait, wait.... The new iPads don't support the split keyboard SOFTWARE FEATURE that is still present in the latest OS release and still working on "supported" hardware? I thought the removal of the orientation lock switch was user-hostile, but damn; this is another level.

I would think it does support it... In my iPad Air (latest model) I somehow ended up stuck with a split keyboard for a bit until I managed to restore it.

It does not support it. Here are the Settings of an older iPad model to the left of the latest iPad Air's: https://i.imgur.com/YaW0eeP.png

Apple repeatedly notes that only certain models support split keyboard (https://support.apple.com/guide/ipad/move-the-onscreen-keybo...). This page was even renamed since iOS 16 from "Use a split keyboard" (https://support.apple.com/guide/ipad/use-a-split-keyboard-ip...), the screenshot of a split keyboard was replaced with a floating one, and the legacy split keyboard information was moved to the bottom of the page.