Not necessarily better data sources, but different data sources and a slightly different approach.
For organic results, the biggest different is that Runnaroo uses Google as the base for web results (similar to Startpage) where DDG uses Bing.
Outside of the organic results, Runnaroo's strategy is to integrate results from different vertical specific search engines who specialize in a niche topic. I call these 'Deep Searches' because they are essentially pulled from the database of the vertical source. It's the difference between getting an link to a website's home page vs. landing on the page and using their own search function to see the results.
For many queries, I believe this can provide higher quality SERP. For example, see the below results for "parkinson research" [0] or "react.js" [1]. The results are a lot more informationally dense than other search engines. Again, not necessarily better, but different.
DDG is still better for many queries(currency conversions, weather, etc), and definitely more polished, but I only launched Runnaroo a few months ago and new features and Deep Search sources are being added almost daily.
So TL;DR, Google results (with privacy) plus additional search results from relevant niche and authoritative sources.
It is. We integrate the Google results through their web search API, and comply with their usage terms of service (as we do with all the data partners we integrate).
Sometimes I still fall back to Google but if that was becoming the norm on DDG, not anymore.
Another thing that helps is configuring custom search engines on Firefox. For example, for me typing `gh something` in the address bar does a GitHub search directly and so on.