Maybe I'm missing something regarding everything around widgets and super apps and how they differ, but as far as I understand, since SDK 4.0.0 you'd get a "super app" that supports glances/glance view as long as you implement it with getGlanceView(). However, if you want to support a similar feature with a widget for pre 4.0 devices, you'd have to compile it as type "widget" by setting the type in your manifest.xml.
If this is the case and you start off with a watch app, when you later implement glance/widget support you can't change the app type of your app meaning you'll not be able to implement the widget for older devices. When changing app type and trying to upload a new version, you'll get an error saying "The app type is mandatory.".
This feature requests is to allow changing between app types, at the very least between widgets and watch apps since they're essentially the same for 4.0.0 and later devices but needs to be set to the correct type for older versions.
If this is in fact not how it's working and I would go another way about implementing widget support after publishing a device app I'm sorry and you can close this issue.
Some references
- https://forums.garmin.com/developer/connect-iq/f/discussion/351754/is-it-possible-to-change-the-app-type-of-a-released-app/
- https://forums.garmin.com/developer/connect-iq/f/discussion/319188/glance-views-from-widget-vs-watch-app
- https://forums.garmin.com/developer/connect-iq/f/discussion/323106/app-type-of-widget
