Is there any custom mount solution to put different options under the drone ?

DJI does not have any additonal camera mounts to use with the Inspire 2. It's solely meant to be used with the current X4S and X5S cameras. Even if you did attach another camera onto it, you would not be able to get a feed from it via the Go 4 app. In addition, you could potentially block the obstacle avoidance sensors.

In my opinion a custom mount would be of tremendous value to some.  Having the FPV camera makes this even more attractive.  A custom mount would allow (using GS Pro) the ability to mount an NDVI, thermal, or other camera that can be fired via camera internal timing to map a farm field or other area of interest.  Images can be stitched together for further processing and analysis.  I for one would love to see this as I think it would only enhance the usefulness of the I2.