The Indoor unit reads the Outdoor unit and makes some of the information available in its own history files. That means that if someone owns both units, they can read the AQI from the outside unit with the inside one.
Once I figured out that was possible I made a pull request to add support to the integration for using this, and that PR was merged in today. The good news is that this sensor will show up for people with both units after the next release.
The bad news is that this is only a subset of data, and not everyone owns both units. The only way to get all of the data off of the outdoor unit is via the SMB share, but there’s no way to get that password. Everyone who owns one of these units should contact IQAir and ask them to make this password retrievable from their app.