Related: does anyone know the "best practise" around digitising photos and images? What file format is used? What scanning equipment? What's the standard resolution/DPI used?
Not sure I can advise on the best practice, but I know how NOT to do it: my buddy just told me that a family member spent untold hours digitizing decades of family photos and documents... all at a resolution of 1024x768. headdesk
Replying to myself: I found this document which lays out how archive.org do it.