See this post for a list of other related container packages that you may want to install with apt: https://forums.developer.nvidia.com/t/unable-to-run-nvidia-docker/195321/2?u=dusty_nv
If you flash your device with SDK Manager, it will install the NVIDIA Docker Runtime for you (I would recommend doing it this way since you have encountered errors here).
Also, since you mentioned Python 3.9 before I will point out that the l4t-pytorch containers use the same Python 3.6-based wheels that are from this topic.