What I am really hoping for, but will laughed at:
Some form of API or interoperability between iMessage and other platforms such as WhatsApp, Zoom, RingCentral, Google Meet, Teams, etc
It is but a pipe dream.
On a more serious note:
1) Ability to back up iPhone to different cloud providers. I do use iCloud, and it would be nice to be able to end-to-end encrypt to GDrive and OneDrive
2) The type of all handling available on Android; some type of call screening facility which is present on Pixel 6
3) Ability to move voice and FaceTime calls between devices on the same account, same WiFi connection
4) FaceTime: Customised "from" address per contact, in addition to the global setting
5) FaceTime: Ability to screen call before answering; similar to Google Duo
6) iMessage invites: Custom domain option
7) Disposable email addresses: Custom domain name option (instead of being locked to iCloud.com domain)
8) Option to pay by crypto in Wallet (don't know if this already exists)
9) Native dialler integration, as allowed within Android
10) Hardware token authentication with iCloud/AppleID (eg Yubi key) as a secondary or tri-factor authentication method
11) Ability to not have to leave OneDrive unlocked to allow iPhone "Files" app to access content
12) Guest mode for iPhone, as with Android (Lockdown Mode)
13) Camera takes photo when wrong face/password is entered