Complex project for an ambitious rockie

Hello everyone,
I would like to make a local app that allows me to do the following things:

  • Navigate a specific site via web view (I was thinking of using a control based on the "prefix" of the navigated url as long as the initial part remains constant (e.g.: navigable as long as the URL starts so "https://www.miosito.com/" ) in case of attempted exit notify the user that it is not allowed to navigate freely via the app.
  • Download PDF files from the site (individual ones are on average 15mb max while summaries are about 200mb), this can be done either via web view or via direct call to the site in the background;
  • Read downloaded PDF files in offline version;
  • Read downloaded PDF files in online version using google docs viewer shortcut;
  • the downloaded files will need to be easily accessible for online reading so I was thinking of a "proprietary" folder in the app where it saves the files and allows them to be used offline.

I expect in terms of screens:

  • Screen Home: You are made to choose whether you want to browse the website or download/read pdfs;
  • Screen Website: You are allowed to browse the specific site and return to the home;
  • Screen Download PDF: You are made to choose which PDF to download from the available ones and download it by saving it in the appropriate folder;
  • Screen Read PDF:
    is made to choose whether one wants to read a specific PDF online or offline;

I thought of including the extensions "viewBigPdf" and "CustomWebView".
I am newbie and need a lot of help to achieve my goal, does anyone feel like helping me in my project?

Thanks for your time and possible support!