France and Russia are to co-operate on a ultra-light reusable first stage demonstrator under the two countries joint Oural programme

The reusable first stage demonstrator was mentioned in this Russian Federal Space Agency (aka Roscosmos) news item on its website

Russian company Khrunichev has developed a flyback booster called Baikal so one wonders if this is what the French are interested in

Roscosmos has declined to comment further and Hyperbola is waiting for more information from the French space agency CNES