I want to install appx Package with $Add-AppxPackage, but I need to install the app on my 2nd HDD, so how to change installation path in PowerShell $Add-AppxPackage?
You couldn't change the install location during the add-appxpackage process, there is no optional parameter for changing the install location in the Add-AppxPackage. You could see the same opinion in the thread:Question on "Add-AppxPackage" powershell command
However, you could try to change the app's install location after the app is installed.The steps for the Windows 10:Setting-->Apps-->Apps&features-->select your app-->Move-->Choose your 2nd Hdd.