Unfortunately not at present.
As you might imagine neither Apple or Google provides any practical mechanism to transfer a current user from one platform to the other for a paid app, so that you would be able to the run the app as a licensed user and continue to receive updates.
There is also unfortunately no mechanism under either the App Store or Google Play to offer a discount on a paid app to a user by way of recognition of a previous purchase on another platform (or for any reason, in fact).
Please note also that TPE 3D and The Photographer's Transit are only available for iOS.
If you have a Skyfire subscription on either Android (through the Skyfire app) or on iOS (through TPE), you can continue to use the subscription on the other platform via the corresponding app.
We appreciate your understanding.