I found a way on how to migrate the app including data from an old phone to a new phone.
You need a bit of 'computer knowledge' to understand the procedure however.
install ADB (https://developer.android.com/studio/command-line/adb) on your PC
Open cmd window in the folder where ADB is located
on old phone: enable USB debug option in developer options
connect old phone to PC ( watch for question popups on phone and answer them)
check if phone is visible to adb : adb devices
commands:
adb backup -apk com.mobeam.beepngo ( watch for question popups on phone and answer them, if your phone is encrypted it will ask for a password (use simple password like the letter 'a' . This command will create a file backup.ab in the current folder)
[the previous command should have backed up the apk as well. However on my phone this did not work so we need some more steps to copy the apk too:]
adb shell
pm list packages -f | grep mobeam
will show the path where the application is stored (in my case:
package:/data/app/com.mobeam.beepngo-2/base.apk=com.mobeam.beepngo )
copy the apk to a folder which is visible on PC:
cp /data/app/com.mobeam.beepngo-2/base.apk /storage/self.primary/Download/beepngo.apk
exit
(you are back at the normal cmd window prompt, don't close the window yet)
Now on PC open windows explorere, navigate to your phone devices Download folder and copy beepngo.apk to a folder on PC
Disconnect old phone
on new phone: enable USB debug option in developer options
Connect new phone (watch for question popups on phone and answer them)
Copy beepngo.apk to the Downloads folder of the new phone
On phone use file manager, navigate to Downloads folder and run the beepngo.apk to install beepngo
On PC go to the command window:
check if new phone is visible to adb : adb devices
adb restore backup.ab (this will restore the beepngo files, watch for popups on your phone and answer quesitons. if you had to enter a password for encryption, please enter the same password again )
Start beepngo and the data from previous phone is visible
