Were the migrating armies free from logistics?

Were the Cimbri and Teutones effectively immune to logistics?

No. They sustained a huge moving population through broad-area foraging and continued movement, and they still benefited from captured Roman supplies.

Migration did not make the coalition immune to logistics. Its people moved in a very large, dispersed body and drew food and other supplies from a wide area as they advanced. Constant movement and foraging reduced dependence on the fixed depots associated with a state army, but did not eliminate the need for food, animals, wagons, and captured stores. The seizure of Caepio's camp had practical value as well as symbolic value. This was a different supply system, not the absence of a supply problem.