This seems like a straightforward question and a simple fix -- can we get the "Unique" and "Percent Unique" options for the Linked Records field type when we click on the column summary??
These two summary options are available for single select, multiple select, single line text, long text, email, URL, and more field types, but not Linked Records. It would be very handy to have within a view. My workaround right now is to create extra formula fields to output the values in the linked record field as a string, and then use that field to get the number of unique values within that view.