Can I scribble & draw at the same time?

Scribble transcribes the handwritten strokes automatically, and there is no API to access that drawing.

PencilKit, for its part, will allow you to have a canvas view and full access to the drawing's strokes, so you can run recognition independently.

Am I understanding you correctly? ... If I add an UIIndirectScribbleInteraction on a PKCanvasView, can I keep the drawing strokes on the canvas and then capture the Scribble also at the same time?

If what you want to achieve is to get handwriting recognition results for strokes in a drawing canvas, I would not recommend the approach you describe. Both Scribble and the PKCanvasView would compete to get the pencil events and draw strokes. You can control if you want to let the user draw on the canvas view, or have their writing transcribed by Scribble, but not both at the same time.

Scribble is not intended to be a general purpose handwriting recognition API. Its main purpose is to allow text entry on text fields.

New in PencilKit on iOS 14 is full access to the underlying strokes in a canvas via PKDrawing, which you can process through a handwriting recognition engine.

Thank you for clarifying. Which handwriting recognition engine is Apple recommending developers choose to go with?