Opening a dialog on field change in Modern UI

I have a scenario where custom code is opening a dialog to ask a question when a field value changes on the screen. In classic UI, it uses a callback command to call an action (non-visible) that uses <View>.AskExt() to open the dialog, and pressing a button on the dialog calls back to the same method. Does anyone have a working example of this scenario in modern UI? ​  ​@Yuriy Zaletskyy 's post here --> https://blog.zaletskyy.com/post/2026/01/20/how-to-create-a-popup-dialog-in-modern-ui seems promising, but it doesn't get me all the way there to get the dialog to open on field change. I think I'm at least missing how to specify the callback for the field without a FieldUpdated handler (which also won't work).