Use the published api swagger to get the endpoints and consume them over a call rest api in a microflow in your other app. You can use non persistable entities to better map the data.
Also:
https://docs.mendix.com/howto/integration/publish-rest-service
https://docs.mendix.com/howto/integration/consume-a-rest-service
Good luck!
Not sure if I understood you correctly but if you need to consume the REST API you can use the Call REST action activity in the microflow of the app where you want to consume the API published by another app.