Just for clarification:
There is currently no sync support on Opera for iOS as present on desktop and android browsers. Signing in to the Opera account website will not sync the browser, just give access to the account via webpage. There is no special native app to webpage integration.
Note: The only syncing available is via the Flow feature that syncs Flow messages and tabs on connected devices.
Why no sync on iOS:
Its an old legacy issue, other platforms are based on the chromium open source and gets sync as part of the package (with a lot of actual coding on top), on iOS this needs to be implemented from scratch to play with the other platforms. Its not a trivial task, but will take months to implement.
When can we expect it:
We intend to start working on the account/sync task the next few weeks and after that it will take quite some time of development and testing before we can launch. A lot of testing. Lets hope for a christmas present.