Assistive Access in iOS 17 is very disappointing for third-party developers. It seems like there's no API to actually opt in to the new system styles/layout that Apple apps use, so you're basically on your own.
I want to support Assistive Access in @broadcastsapp, and had real first-hand experience this year with trying to tailor iPhone for a family member in hospital who could barely see/operate it. Building a whole alternate UI from scratch myself isn't a great solution. I had hoped for more