After lot of research and consulting with various teams we have decided to go through below approach.
We will use the OCP's out of the box export utility to generate xml file and will write custom script to download the images to file server. We will also use the custom script to save transnational data to sql server database We will then use Sitecore Data Exchange Framework and use xml and database providers to import the data in to sitecore.
If anyone in future come to the post with similar requirement, they may get some idea on the approach part we took hence mentioned our approach here.
Thanks,
Kapil