I use SearXNG since half a year or so I think. It can be a little bit slow at times and some source engines will be deactivated temporarily. But overall its good enough for my daily use. I don't search the web too often anyway and often use the search on the services webpage directly (Steam, Wikipedia or other stuff in example). One can default to SearXNG and in some cases use DuckDuckGo or Startpage (instead Google) for alternative results.

However sometimes an instance is offline temporarily or forever (but never tested after forever, so not sure about that). In those cases I have to switch to a different instance in Firefox default search engine, which I have bookmarked a few to choose from. So be prepared.