I need to know if there is a possibility to get all Azure AD users using PowerApps or not.
You cannot get all Azure Ad users using PowerApps, whereas you can list the details of a single user or users within a group.
Make use of Azure Ad connector that needs administrative permissions for your account like below:
Connect Azure AD in the app,
Go to the Data tab -> Add data-> Search Azure AD -> Select Azure Ad connector -> Connect
To get users within a group, make use of below query:
Users= AzureAD.GetGroupMembers("Your_Group_ID").value
To get details of a User, make use of below query:
OnSelect = ClearCollect( colAzureUserDetails, AzureAD.GetUser(txtAzureID.Text) )
To know more details, please refer below links: