If those sites have a search box on them, then they usually have a query parameter. For example, HN has https://hn.algolia.com/?q= https://hn.algolia.com/?q= Yo

If those sites have a search box on them, then they usually have a query parameter. For example, HN has https://hn.algolia.com/?q= https://hn.algolia.com/?q= You could have a site that autocompletes all of these and returns the results if the site has an api, or at least generate the result links so that you can click them.