A. Write a before plugin on \Hagento\catalogVtodel\ProductRepository: :geti_ist() and register the search criteria passed. Write an event observer to 0 listen for the event cataiog_product_coiiection_ioad_before. Iterate through the registered search criteria, and if found, apply the needed join and filter to the events scollection.

B. Add a CUStOm filter to the Virtual type
"agento\Catalog\Model\Api\SearchCriteria\CollectionProcessor\ProductFilterProce5sor for supplier_id field. In the custom filter, apply the needed join and filter to the passed $collection.

C. Write a before plugin On \Magento\Framework\Api\SearchCriteria\CollectionProcessorInterface:
:process(). Iterate through the $searchCriteria
provided for supplier_id, and if found, apply the needed join and filter to the passed scollection.