I've answered myself: I bought the H7 and it is not (yet) recognized by the Jolla.
I suppose if bluetooth LE will be supported, it is probably just a matter of updating the app (I mean, more work on OS than on the app).
I've also read that in android world, some apps implements their own bluetooth library but I personnaly don't think it is a good idea.
I really don't wait anything for now, especially because the app is free of charge on openrepos, and it is already one of the best app available in this OS.

But I am more than ready to buy an updated version when Jolla harbour will propose paiement.