Classifications can be used for Traffic/Conversion/Campaign variables. 'None' item cannot be classified. However, you may breakdown that line item.
I hope this answers your query.
Is this possible for child classifications too? I hv two classifications for trackers. A parent one and a child one which groups them. In the child classification I'd like to set the "Nones" to "direct". I tried to classify it with multiple classfication (as described here: https://marketing.adobe.com/resources/help/en_US/reference/c_classifications_example.html) setting Key value "*" and parent classification "~none~" as well as parent classification "None" (as it appears in the report). (See screenshots) But this didn't change anything.
So question is: can I use the "~none~" only for parent classifications?
Correct renaming the none key only works at a parent classification level.