Use/View Only Group's Media Items in CKEditor Media Library Widget

I already have the plan to do this feature. But unfortunately, I don't have the time. Most probably it will be a submodule in Group Media Library → module. Also it would be nice to have due to ✨ Allow 3rd party to easily add new params to media_library_opener_parameters Active fix before.
Anyway, if you want this feature now, you could do it in a custom module by swapping the plugin class (as suggested by the issue)...

Thank you for that information. I might go ahead and implement it myself!