Ionic deeplink : help for beginner

i have an ionic 5 application (published on ios / android stores) with Angular/Capacitor, and i would like another app to be able to open my app on a smartphone.

So I have to add a deeplink on my application, correct?
I check this :

But i don’t understand the configuration :

`URL_SCHEME` - the custom URL scheme you'd like to use for your app. This lets your app respond to links like `myapp://blah`

Can I choose anything? Or does it have to match my app / package name from my current config?

`DEEPLINK_SCHEME` - the scheme to use for universal/app links. Defaults to 'https' in 1.0.13. 99% of the time you'll use `https` here as iOS and Android require SSL for app links domains.
`DEEPLINK_HOST` - the host that will respond to deeplinks. For example, if we want `` to open in our app, we'd use `` here.

I don’t have a site or public url to provide here. It’s just a ‘local’ application. What should I put on?

Thank you for your help !