Changing a single instance of an icon

The API for changing icons globally has been wonderful with the small exception that in some spots I want to use a different style/weight (generally due to being bigger or smaller) but I can’t figure out how to select icons in specific spots.

For example: With the chat icon, I would like to use a linear icon in the topbar, but a filled icon in the dropdown user menu.

The API changes both without differentiation. Is there a way I can target them individually in the script, or should I use CSS for one of them instead? My hesitation with using CSS is that it seems like the API change is seen as the proper way.

Did anything ever come from this? Are we able to get this implemented as I require single switch of an icon as well.