DuckDuckGo's results are a compilation of "over 400" sources according to itself, including Bing, Yahoo! Search BOSS, Wolfram Alpha, Yandex, and its own web crawler (the DuckDuckBot); but none from Google. It also uses data from crowdsourced sites such as Wikipedia, to populate knowledge panel boxes to the right of the search results.
Source: Wikipedia
So it's definitely not a "proxy to Bing" but it does use data from Bing.
There's OsmAnd and Organic Maps (and probably more). Both are open-source apps, use Openstreemap data, and work offline. You can get OsmAnd+ for free on F-Droid. If you want support the devs you can buy it in the Play Store. There's also a free but limited version there.