Suppose you create a Copilot Studio agent and you want to share it with users either on a Teams channel or the M365 app. You can go to Channels and select Teams and Microsoft 365 Copilot app.
But if you want to share it with a specific user or entire org, click on the 3 dots and click on Share.
Now select a user or entire org (My organization). Note that it gets the list of users from Entra ID for that environment. If you select "My organization" — it will share with all users who are in Entra ID of that specific environment.
Even if a user is present in Entra ID but does not have a role in that specific environment where the Copilot agent is hosted — it will still be shared to them and the user can still use it.