Don’t rely on early tests with BIN checkers. The latest explanation for this seems to be that Revolut uses an implementation of what Mastercard calls “Account ranges”. After a universal 6 digits BIN, further digits define, in the case of Revolut, the country of a card.
Some, me included, assume that this is how Revolut will control availability of services like Apple Pay. They need to control this by country, cards gerenally issued in France won’t do the trick.
You should be able to add the Metal card to your iTunes account now (same country as your Revolut account).
Try http://binbase.com/search.html , this BIN checker shows you that the same BIN is used for different countries, and France is not the only country information for this 6 digits BIN.