Problem with nbdev and notebook2script

Thanks @dynamics
Actually the issue was the export file name expected the whole file path in Google Colab.
So it was fixed using the following code:

path = Path('.')
path.ls()
gdrive = path / 'drive/MyDrive/Colab Notebooks'
gdrive.ls()
import nbdev
nbdev.export.nb_export(gdrive/'pet_classifier.ipynb', 'app')
print('Export successful')

Reference: Error with nbdev.export.nb_export

I’d one more issue, this exports whole notebook and not just the cells with #/export as seen in the lecture. Any clue on how to fix this?