Another useful feature: Custom bangs! You can create bangs for any website you want.
I’ve deployed a test instance, so you can try and see how it works: https://interro.deno.dev/. On this one, the fallback search is Mojeek, and there is a special bang !ky that will search the contents of my website.
The page is very much WIP; interro was built to be used from the browser’s search bar 😅