Get-Credential does not support Smart Card user name hints
If you utilize Smart Cards with certificates that are not directly linked to users (no suitable user DN in Subject and no UPNs in SANs), you are able to link a single certificate to multiple accounts dynamically with the caveat that users need to provide explicit user name hints during logon in order to log on.
User name hints need to be enabled via GPO or registry settings ("X509HintsNeeded"), after which all standard credential dialogs in Windows support them, except PowerShell's Get-Credential. This effectively prevents using PowerShell remoting with such Smart Cards / certificates if different credentials are required.
In today's landscape where Microsoft recommends explicitly tiering your infrastructure and user accounts and using secure methods of administration such as PowerShell Remoting, the omission of this feature is a big letdown. It also reinforces bad habits because Remote Desktop fully supports this scenario while PowerShell does not.
This feature should be implemented.