It's always nice to see a new face in the Community. After testing this in my QuickBooks Online account, I've discovered that a sales form doesn't include the pictures of Products/Services. However, you can add an attachment by going to the sales form and clicking on Attachment in the bottom left-hand corner. Note: The attachment's maximum size limit is 20MB.
I know how useful this feature could be to you and other users, so I'm going to personally submit feedback to our Product Developers. They take this feedback seriously and try to consider different options for new upcoming releases for QuickBooks.