Is it possible to move an entire project from one namespace to another namespace? And if so, what are the prerequisites? What roles / permissions are needed? Is it possible via the UI or via the API only?
Within namespaces that use the same File System and Role Set, this is possible in the API only, using the same API as moving resources. This requires you to have permission to create projects in the destination namespace, and an owner-like role on the project being moved.
It’s not possible to move projects between namespaces that use different File Systems (usually meaning they are owned by different Enrollments) or Role Sets though.
Just to add to this. The API call looks something like this.
curl -XPOST "$STACK_URL/compass/api/folders/<NAMESPACE_RID>/children" \
-H "Authorization: Bearer $TOKEN" \
-H "Content-type: application/json" \
--data-binary '{"children": ["<PROJ_RID>"]}'
This is an internal API, so it may change in the future.