what the new Microsoft Edge is doing is to give users 2 options:
1. PIN websites to taskbar, start menu and desktop easily for fast access. 2. Run those PINNED websites in a different, minimal UI.
there is no conversion happening, Edge, Google, Chromium don't convert websites into web apps. I'm mentioning that because in the new Edge, it's called "install a site as an app" which is misleading. Edge doesn't install any website, websites are not UWP apps or programs written in C++ to be able to be installed. it's all just Pinning.
To PIN sites or to install sites as an app, there are 2 ways: