The Algolia Visual Merchandiser tool in Magento 2 allows you to promote specific products by displaying them on the category page so that you can highlight those products before your users search for a query.
*Please note that you'd need to enable “Replace categories page” by selecting “Yes” in Stores > Algolia Search > Instant Search Results Page.
You can pin/unpin products using this tool, please note that the number of products you can pin in your Magento admin is configured in your Stores > InstantSearch Result Page > Number of products per page, the limit is 50.
If you'd like to pin more than 50 products for your category page, you may look into Merchandising Category Pages using Rules. By default, you can pin up to 300 products per rule.