Hello @Jonny Klaas
Thank you very much for reaching out to us I will go with your second concern first can you please verify if the password writeback connectivity in the Azure portal is showing up and running if Yes then please try to toggle the password writeback service on and off and re run the PowerShell to see if its reflecting or not also if you see connectivity failure in the below screen shot then follow this article for troubleshooting issues related to password writeback.
And coming to you first concern user won't get the notification to change the password if they are logged in in order to revoke the session you can use the below Graph API query to revoke the session for a user.
Revoke-AzureADUserAllRefreshToken
-ObjectId <String>
[<CommonParameters>]
Also Get-AzureADUser -ObjectID username@keyman .com | Select PasswordPolicies, PasswordProfile | fl will display the password policy of the Azure AD not the local AD that is the reason it is showing none for you.
In case you have any questions on the same, you can surely let us know and we will be happy to help you further. If this post provides you the answer you were looking for, do accept it as an answer in the interest of community members with similar queries. If this does not answer, please ask further in the comments and we will happy to address your concerns.
Thank you.