currently, any search query without a bang redirects to google by default.
we can have a dropdown in the home page that let's you select a search engine of choice.
this can basically just append another query param at the end, something along the lines of https://unduck.link?engine='ddg'&q=%s if you want ddg to be your default search engine.
users can then copy this and go on with the pasting as they do normally