Merchandizing specific items in Algolia works by pinning specific records. It does not currently support the functionality to pin either products (as opposed to variants) or categories of products. In other words, there is no way to "reserve" a slot for a specific type of search result -- it's always just one specific object/record.
One option to achieve a type of "categorical" pinning would just be use a second, filtered request to the same index. So for each search request, you would use a multipleQueries call that contains two separate queries -- both of which directed at the same index. The first query would be filtered specifically to that "category" and you'd only display the first result (or however many you wish to display). The second request would be unfiltered and would display its normal results (alternatively, it could be filtered to exclude that category of data.)
The caveat to this is that it would need to be specifically implemented wherever it is needed. It would not automatically occur based on a specific search condition (like an Algolia Rule.)
Last reviewed 11-10-2022.