Is your feature request related to a problem? Please describe.
No, it would be a new control.

Describe the solution you'd like
I would like to have the TokenizingTextBox control from Windows Community Toolkit. While it's not part of WinUI itself, this library has already implemented WCT controls such as RangeSelector (RangeSlider) and SettingsExpander.

TokenizingTextBox it's similar to an AutoSuggestBox but allows to pick multiple items and displays them as removable tokens in the controls itself (up to 5 in the original control):

Additional context
There is a project which ports this control to Avalonia but it's not compatible with Avalonia 11: https://github.com/puppetsw/AvaloniaTokenizingTextBox