it is not possible to do this because as already mentioned 2 days ago:
after building your app the assets folder is read only... your method only works in the companion app...
therefore the simplest solution for you is to copy everything you need for that webpage into the assets of the app without need to unzip anything...
as most probably these are a lot of files, you get a problem while building the app, therefore as also already mentioned earlier follow this advice
however you have to consider @TIMAI2's advice, too...
hope that helps...
now it is your turn to try something
Taifun.