Just use the wildcard. Say I want the PFN for Microsoft Teams but I don't know the full name to look it up. I narrow it down by placing asterisk before the t and after the s in "teams":

PS C:\Windows\System32> get-appxpackage "teams"

Name : MSTeams Publisher : CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US Architecture : X64 ResourceId : Version : 24295.605.3225.8804 PackageFullName : MSTeams_24295.605.3225.8804_x64__8wekyb3d8bbwe InstallLocation : C:\Program Files\WindowsApps\MSTeams_24295.605.3225.8804_x64__8wekyb3d8bbwe IsFramework : False PackageFamilyName : MSTeams_8wekyb3d8bbwe PublisherId : 8wekyb3d8bbwe IsResourcePackage : False IsBundle : False IsDevelopmentMode : False NonRemovable : False IsPartiallyStaged : False SignatureKind : Developer Status : Ok