Yes, you can upload pictures to e.g. a service report. E.g. we have an equipment repair app and I added in the Service Table a File field. The technician goes to create a service report and is able to upload a picture. Pretty handy, especially if you have the same problem come up in the future, you can easily go back and verify via pictures.
I also concur about a signature. I would think there would be a way like in Adobe to electronically sign a document after verifying the user and either putting a text version of the signature with "Verified" or possibly uploading an image of the person's actual signature.