Anyone building (or in this case, buying) a search engine takes a fight they cannot meaningfully make impact.
1. Privacy is a feature, not a platform. If the search engine cannot deliver better results than google or bing (a tall order) then there is no reason to use it no matter how private.
2. Google has a 20+ year head start and billions invested. You will not catch up playing the same game (eg - broad search). Google, for all its faults, is amazing technology. If you try to be a general search engine and compete I do not see a win.
3. Find another strategy, like BETTER search results within a niche. Curated by subject matter experts and enthusiasts.
4. Source your search results from trustworthy data sources. SEO has ruined search. Google setup the rules and the Black/Grey/Whitehat practitioners out-smartted them every step of the way. It is full of crappy data sources.
5. Curation, not scale is the key here. I don't see a win for Brave.