How to grant access to all applications, in SAP Cloud Platform, Cloud Foundry

Hello experts,

I have a question regarding oauth and client-to-client.
I’m developing an app, exposing a service
I’m defining a scope for access
I’ve learned that for app-to-app scenario I can use “grant-as-authority” and specify the app which is allowed

What I don’t understand:
I want to deploy an app, want external clients to consume my service, but I cannot know all the clients.
I’ve checked the documentation but I don’t see how to grant my scope to <all> apps
I’ve tried with asterisk:

"grant-as-authority-to-apps" :
[ "$XSAPPNAME(application, *)"]
"grant-as-authority-to-apps" :
[ "*"]

But that doesn’t work

Isn’t it possible?
Have I misunderstood the concept?
How should I proceed?

Thanks for any advice.