It depends on the show, moreover the show provider, and what their regulations are.
Typically it is against the rules for exhibitors to “sub-lease” room within their space to other companies for blatant promos, or for exhibitors to allow other companies to represent themselves within their space. The exception to this is if a parent company decides to highlight their portfolio of brands or sub-groups/companies.
It is not in a show’s best interest to allow paying exhibitors to let non-paying exhibitors in the door with their product.
Yo’s example is a bit different, it is not uncommon for a company to display products that they don’t manufacture, however this is usually in the context of a setting. Like for example a company may want to display/demo their product, which is a component of a system that is typically made up of a variety of other company’s products. Another example would be more of a setting, like a living room, the exhibiting company might make some sort of smart home product, but they need to include other company’s products to set the stage and demo their own product.
I agree with Yo that you sho9uld approach the other companies’ event marketing folks to discuss integrating your product into their displays, however you likely won’t be allowed to have anything more than your product there, no signage, graphics, or digital content that promotes it. Their exhibit staff can explain what it is to attendees, but they technically can’t promote it or gather leads for you, however, if you are exhibiting at the same show they can direct attendees to your booth.
Is there a reason you wouldn’t just exhibit the product yourself? There’s tons of options for exhibiting.