You may find the discussion on this community post helpful.
The discussion will lead you to this github readme which has some additional instructions that you may find useful.
From what I am seeing, it seems that the VPN can support raw images but that is dependent on their size. Assume you are sending an HD image at 30fps, that can be called equivalent to 1080x720x3x30 = 70 MB/s or ~0.5Gbps. Assuming the VPN can support this, your ethernet/wifi adapter must be able to handle such large data rates too. This is why compression is required.
Depending on your requirements and compute availability, you may try anything from as simple as JPEG compression to theora compression or H264. I would recommend checking out this repository for a relatively simple and quick way to get compression native to ROS2 running.