Using Framework7 or Electron

I’ve never created a native application using Framework7 or Electron. I have several web applications that are dynamic. It would be great to convert these to desktop and/or mobile applications.

So my question is:

Is it possible to retroactively add Framework7 or Electron to the existing apps, or do I have to initiate the creation of the desktop / mobile app by adding Framework7 or Electron first?

Thank you for your guidance.