God dang it, after spending two hours looking at this, as soon as I created this post and had a coffee, I found my mistake.
I have to check inside of the widget metadata to see the widget and not just inside of the item page…
sorry seems like the issue was between the chair and the screen!
Edit #3: the other part of my problem, the difference between the list widget and the default one, is elegantly explained by @JustinG on the post below.
You just need both the standalone and the list widget. These two metadatas are different. The semantic cards and group lists use the list item widget. The item details page and semantic model items pane use the standalone widget.
To my knowledge, there’s only one place. In a layout page when adding a widget, at the bottom of the list of options that comes up, there’s a Add from model option or something like that. If you click on that option when you are adding something to the cell grid of the layout, then the item you selected from the model popup will use it’s default cell widget.