You could create your own custom or multi-optic by looking at the existing ones, merging them in a text editor, and hosting the file somewhere accessible, like github.
See https://trystract.com/settings/optics , the top 10k list also has a comment telling you how it was generated, so you could just create your own top 1k or bottom 3K list, just change the Discard to Boost(0)if you want to limit your results to only these sites.
Hmm I just checked, they’re all live and their status page for each link has no outages. I would check any content blockers etc. that you have, I suspect it’s a problem on your end. They do use different domains for their blog, feedback, and help KB etc.
My best guess is that a DNS record is messed up on their end, and since I’ve been to those pages before relatively recently, the cname or A-record is still cached for me.