Hello Bastien,
Migration from GD platform to GD cloud is not yet supported or documented on our side.
It might be theoretically possible, with some manual effort, but so far we don't have any guidelines for that, as the actual process would depend on the solution.
In the future, we plan to have API or tooling for the migration, but we are not there yet.
As it's quite small scope migration, I guess it's better to do it manually than trying to figure out some programatic way. And it's also possible to utilize our professional services team.