Hello, can a companion (Junk, Jax etc) spend two MPs to carry a supply crate? It is not an interact right?

Correct

It's claim, not retrieve (which would be forbidden for figures who cannot interact), so yes, it's possible - which is the reason why Junk Droids might still be a thing.

But with the new map coming into rotation, Nal Hutta is that much closer to phase out. (After the ToL wave comes out.)