A surprising fact I /do/ know about DDG: they don't update bang searches anymore, which was one of my favorite differentiators. This feature adds a lot of utility to DDG as a browser default search engine.
You can search "!w Gabriel Weinberg" and it will open the Wikipedia article because of the leading exclamation mark and w. If a site changes their search url, you can submit the precise new pattern they should use for a redirect. If a new service pops up, you can use the same form to request a new search prefix. These form submissions could give someone at DDG an easy interface to verify quickly and approve or reject them.
These form submissions get ignored and have been for years at this point.
Are you aware of Firefox's search keyword feature? You can bookmark the URL of a web site's search result page, replace the search text query parameter with %s, and enter a keyword in the bookmark details. From then on, entering that keyword followed by some new text in the address bar will perform the new search.
You can choose keywords that don't start with !, so typing them is easier than using Duck Duck Go's bang feature.
This functionality has always been available in Firefox: Just add a keyword to a bookmark.
A primary problem is we get overwhelingly spammed with submissions. They are not completely ignored. We have maintainers, but as a relatively small team given the surface area of what we're working on, they have been de-prioritized. That said, I think some better tooling could probably get be put in place at this point to help us.