I don’t know all of the in’s and out’s of how PWA’s work, but yes, the way I understand it is the Add to Homescreen popup is triggered by the browser if the app is structured as PWA. From what I’ve read, once a user accepts or dismisses the popup, the browser remember’s that within the browser cache and will not reissue the popup. Also, from what I’ve read, there isn’t any way for glide to re-trigger the popup.
That is why it was mentioned earlier to clear your browser cache as a way to get the popup to show up again. As an alternative, the user can install the app by opening the browser menu and tapping on Add to Homescreen, but it’s imperitive that the user is using chrome on android or safari on IOS as those are the only mobile browsers that fully support PWA installation.
If the popup doesn’t appear on a fresh install on a new device, or after the proper clearing of the cache, then that might indicate an issue with the app that’s not allowing it to be recognized as a Progressive Web App.