Thank you for your message. None of the current French senses of dépareillé lend themselves to a translation of 'unmatched, unparalleled', so I'll pass this to our FR base to see if there are any senses to add.
Only that unmatched is a synonym of unparalleled. We don't say unmatched for things that don't match. Chaussettes dépareillées are odd socks or mismatched socks (or possibly just socks that don't match). So, if dépareillé cannot mean unparalleled, there's nothing to add. Thank you!