종류가 많네요.

https://wordpress.org/plugins/tags/pwa/

SuperPWA에 보면,  아래와 같이 되어 있는데,  offline이 되어도 한번 방문한곳은 데이타를 볼수가 있다는 것이네요

QUICK DEMO?

• Open up SuperPWA.com in a supported device.
• Add the website to your home screen either from the Add to Home Screen prompt (Chrome for Android) or from the browser menu.
• Open the app from your home screen and you will see the splash screen.
• Turn off your data and wifi to go offline and open up the app. You will still be able to see the app and browse the pages you have already visited.
• Browse to a page that you haven’t visited before. The offline page will be displayed.