I don‘t think I have used more than 1000 different sites in all development searches ever. It‘s the stack exchange network, github, official documentation, non-github official issue tracking/communities and some high quality blogs. That seems very manageable. You could probably index that into one elasticsearch and one sourcegraph instance. Add a little more specific faceted search, add back powerful and precise query syntax and still maintain "just past in whatever and hit the first result" functionality. I‘m likely underestimating the breadth of other developer needs than my own. I don‘t know.