How can I get user list when I create condition flow?

Hi, everyone.

In Homey’s default flow push notifications, you can get the list of users registered on my Homey Pro.
I want to create and provide a flow in my app that I’m developing,
but is there a way to provide the user list as an argument in the flow, similar to this?

It is probably a callback argument, so you will need to create a function to get the users and fill the list dynamically.

The autpcomplete Argument is used:

But you need to read ecisting users. I don’t know if this is possible from an app without WebAPI scope.