We see that there is no ALM capability between apps in New UX. Currently as a work around, we are creating a duplicate of the app and relinking all the pages to the required model.
However, this approach is really painful as relinking all the pages one by one is really tedious and there are high risk possibilities of missing out relinking a page to the required model.
Request to please suggest any other approach for the sync between apps.
There is a better way.
Link multiple models to one app and make the changes in the pages on your DEV. But only publish after pushing the revision tag to prod.
Here's an article.