So, this is not a proper answer to your question. (The closest I’d give there, personally, is DDG, Qwant or Ecosia, all with their own caveats). But, I’ve been evangelizing a bit in favour of helping Mwmbl develop further.

Basically, it is an attempt to do for search engines what Wikipedia did for encyclopedic knowledge. It’s still basically just a dream with an interface that’s experimental and a search index still being built, currently seemingly bottlenecked by available (monetary) resources.

Oh, and a matrix community, where the actual community work seems to be happening.

But even though it’s an infant with not that much more than a dream at this moment - I think their project shows promise, in audacity to challenge search engine giants alone, if nothing else. Currently, I am using it as my go to “first search” search engine, helping with curating results if possible (although, truth be told, in the past weeks most searches did not give anything useful at all). I also have the index building web crawling script running on the same server as my Fediverse instances - but there is also a firefox extension for more casual volunteer crawling without a cli script.

I can’t sell this as a “proper” search engine, but still, am happy in evangelising it to anyone interested in supporting what tries to become a proper, open search engine not just on FOSS software, but FOSS principles.