Possible to do an external command (non Pyrevit ) through pyrevit?

[Jean-Marc (Jean-Marc Couffin)]

No, a Revit builtin command is a PostableCommand
Example

Opening Dynamo Player

an bit of an example from Autodesk.Revit.UI import UIApplication, RevitCommandId, PostableCommand Command_ID=RevitCommandId.LookupPostableCommandId(PostableCommand.Undo) uiapp = UIApplication(doc.Application) uiapp.PostCommand(Command_ID)

and doc ApiDocs.co

there is the PostableCommand enumeration
try the <> at the top right of the page for samples