3D product viewers do not negatively impact the SEO of a website, and even the opposite. Since search engines consider the content of an iframe as belonging to another website, it will not have a direct impact on the SEO ranking.  However, one aspect to watch is the size of the 3D model, which can slow down the loading of the website. Indeed, a too high loading time can negatively affect the user experience, the technical referencing and consequently affect the global referencing.
To avoid slowing down a website when an iframe containing a 3D model file is integrated, it is possible to add the attribute option loading=”lazy” in the iframe shortcode.
With this delay option, the iframe will only load when the guest scrolls over the page (in real time) where the iframe is located. The page will not be negatively affected by the loading of the 3D model display since it will only load when a user arrives at the precise location of the model. Before that, an image of the 3D content will be shown.