not kotlin but kotlin colored But, let me give you a pointer anyway;
You could take a look at ProductFlavors
https://developer.android.com/build/build-variants
Using ProductFlavors, you can have the Release and Debug versions of your app use different package names, and therefor have both versions installed on the same device.
In your case;
This would mean you can a debug-version of your new app,
and the release version of the old app installed at the same time.
If you need release versions of both your old and new app installed at the same time;
You can add another ProductFlavor to the new app, with another package name (
applicationIdSuffix
);
Hope this helps! Good luck!