I gave DDG Privacy Essentials a run on my ChromeBook and on Ubuntu Focal Fossa. It seems to work fine and doesn't interfere with my default search engine. However DDG PE 2021.4.8 on macOS changes the default to DDG. The only way to revert back to another engine is to disable DDG PE.
This extension has had issues... https://latesthackingnews.com/2021/...bility-found-in-duckduckgo-browser-extension/