Once upon a time, when there were actually a bunch of search engines to compare results from, we had Parallel Search Forms. I won’t call them an “engine” because all they did was display the results from several search engines side by side.
You had one form to enter your search terms and the site would query 2 or 3 search engines simultaneously, displaying the results side by side for comparison.
Example: You can see the remains of one here (opens in new tab) as an illustration.
I would love to have one of these today, setup like this:
Privacy Search engine #1: Duckduckgo - DDG uses Bing as the backbone of their search.
Privacy Search engine #2: Startpage - SP uses un geolocated, un personalized Google.
Privacy Search engine #3: Mojeek - uses their own index.
This would make it easy to compare search results of the first couple of pages of each AND how many ads are on those pages all in real time.
This was also posted to /en/search-engines.