alt Hacker NewsWell sure yes, I don't contend with the fact that its hard, but if the top tech companies joined their heads I am sure if for example, Meta, Apple, MS have enough talent between to make an open source index if only to reap gains from the de-monopolization of it all.
All these companies have the exact same business model as Google (advertising) and have the same mismatched incentives: good search results are not something they want.
Google Search sucks not because Google is incapable of filtering out spam and SEO slop (though they very much love that people believe they can't), but that spam/slop makes the ads on the SERP page more enticing, and some of the spam itself includes Google Ads/analytics and benefits them there too.
There is no incentive for these companies to build a good search engine by themselves to begin with, let alone provide data to allow others to build one.