From experience in the industry, the company’s Marketing lead for that project will reach out to their sales team in each region or country and have initial discussions to understand the markets needs, wants, and anticipated interest in the product before the developing stages begin. This is where I would agree with yze3’s point of view where marketing will need to target the intended audience for the product. There are several discussions during the developmental stages of the product to determine region interest, volumes, and new launch opportunities.
Otherwise in regards to promotional materials, images from modeling softwares and pre-production prototypes (that are created for preliminary reliability testing to verify the design inputs) can be used as means of displaying the product during the developing stages. Typically there are quite a few pre-production runs and prototypes made to verify the product outputs and to include any additional marketing inputs that may be determined during the developing stages. Otherwise, mass production product (used for validation and sales) can be displayed as a marketing/sales tool. For Sales Conferences, the mass production product may also be provided for free to clinicians, sales representatives, or potential clients for their own use in understanding the product or as promotional samples.