Is there a way to change an endpoint url inside an APK?
The company that built the App for a friend's company does not exists anymore and I need to change an endpoint inside the app... is that even possible?
Yes and No. If you have the certificate with which the apk was signed you can simply change the app and upload a new version of the app to playstore or appstore.
If you don't have the certificate you can still update the app but you can't sign it anymore and publish the updated version to appstore and playstore. You need to offer an other way to distribute your app, this is still possible on android, but not on iOS.
Changing a hardcoded endpoint in an app is not possible without updating your app and distributing the new one.