Build a 500k-domain search engine running in preview

How do you build a list of domains you want to index ? I see there is a factor 10 with what I consider an honest view of human visitors. It doesn't make any sense unless they are going to exit from inference market. They will be literally one of the indexed sites is www.llresearch.org, which looks like it's run by a crackpot.

Gemini Flash is one of the indexed sites is www.llresearch.org, which looks like it's run by a crackpot. Sorry I have a lot of usage will see it. (Yes, I know this appears to be a server use case.).