<PackageReference Include="System.Security.Permissions" Version="10.0.0-preview.3.25171.5" />

FileDialogPermissionAccess

Specifies the type of access to files allowed through the File dialog boxes.
namespace System.Security.Permissions { [Flags] public enum FileDialogPermissionAccess { None = 0, Open = 1, OpenSave = 3, Save = 2 } }