There are many reasons why you might want to use a web app of your database instead of a full app, after all Odoo works on the cloud so the web app is a great choice.

On iOS:

To do so you must add your database to your homescreen, simply go to your database in safari (log in is not necessary yet):

Then press the share button and there you will have the option to add to home screen:

After adding to the home screen you’ll see the icon pop up on the home screen:

And after going to the webapp and loging in, it works just as good as the app with full screen:

For Android users it will depend on your browser of preference but you can check these instructions for chrome:

1- Click on the three dots and add to home screen:

2- Input a name for the app and press on add:

3- You should be able to see the icon on the home screen: