DDG uses Bing’s index I believe, so they’re just reranking results for you + proxying queries. The big indexes are generally low quality and DDG can show you only results from them. Kagi seems to train theirs on small web and uses user rankings to adjust, which helps a lot.
They are not without issues, they’ve been pushing for open indexing as indexing is getting harder due to AI scrapers. Cloudflare and Reddit for example make it much harder now (Reddit has an exclusivity deal with Google), but I do get results from both.











You can make shortcuts/bangs, and you can create “lenses”, which allow you to create filter presets on your queries.
There’s a default fediverse one available.