To save the web app to your homescreen, so it looks like a typical, native app on your phone, follow the intructions below:
If you're using an iPhone, open your app link in Safari.
If you're using an Android phone, open your app link in Chrome or Firefox.
Tap the Share button on iPhone or the 3 vertical dots on Android.
Select "Add to Homescreen"
Note: If this option is not available from the Share Sheet, you're in the wrong browser! Copy and paste the URL into the correct browser listed in Step 1 above, and try Step 2 again.
Name the shortcut, and add it to your Home Screen.