Before everyone just started using Docusign anyway, I'd bought houses with a phone "scanner". LOL.

I don't think I started with it, but for a very long time I've had an app called TinyScanner that's good-enough at edge detection, can de-noise or make a document entirely black & white, and can glue multiple pages together into a PDF. The results look better than plenty of flatbed scanner results I've seen, if not as good as the best of those.