In what context should these colleagues be able to see these users? In any Moodle, for those users who can see participants at site level, there's the ..user/index.php?id=1 page to consult with the full list of users, but without the delete and edit tools.
The permission for this would be:
Thanks for the message.
That's not a screen I've seen before, but have been able to reach it using your URL postfix.
Is there a standard navigation path to arrive at it?
They would need this at the site context in order to be able to browse all users.