Procreate is a drawing app with a fantastic smudge tool. I have been using it to experiment with drawings that are half drawn and half photographic. I am fascinated by this meeting. I either start with a photo, smidgin it until it has all but disappeared, and then drawing on top, or I do a drawing, and then try and a photographic behind the drawing.
The discipline of drawing from life and from sight is very different from tracing on top of a photograph. I don't wish just to use a photograph to make a fake 'well observed' painting - I am trying to achieve a balance or interplay between the photographic and the hand drawn. I don't know if I am succeeding or not, but it it a very enjoyable process.