I use https://chrome.google.com/webstore/detail/personal-blocklist... but it should come with pre-compiled lists, like uBlock Origin.
This feels like an application of the 80/20 rule. I might not always find what I need in just that offline index, but the times I do would seriously disrupt google.
Oh, I wish there were a way to rate the results in a opposite way. Maybe it's just me, but sometimes I want even mark some site as 'a hidden gem'. Usually it's something rather niche though, like a bunch of great little articles about anti-aliasing filters design and sampling, full of engineering wisdom from the decades of experience. So I think it would be perfect to have a way to tag it by some topic.
I don't have a CS background so I'm not sure, is this a reasonable solution?
But having a way of making sure that a certain topic or genre of sites is well indexed locally would work. I.e. "my" top 100k. Oh, how awesome would that be.