You don't have to, cus the wefwef.app link still works. But if you want to, go to vger.app and do the same process you did to install the PWA app on your home screen. On Chrome, tap the settings tab, click install app. On Firefox, it doesn't give you the option to install from the install webpage, instead there should be an install button in Firefox's more menu.
On my Pixel using Firefox, the name updated to Voyager, but the icon is still a black circle with a "W" in it. Is that normal, or is there a way for me to get the colorful icon?