I currently use OVH as a registrar, but I would like to be able to use terraform up my domains to use another DNS provider (for exemple AWS Route53).

This does not seem possible at the moment, you only have resources to change the content of a zone, not nameservers.

An ovh_domain zone would be useful (only working if a domain exists on the account, obviously). It could be use to set up nameservers & DS records for a domain.