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.
I tried finding information on what indexer they are using. Are they using their own?
Edit: says this in the readme:
The commoncrawl organization for crawling the web and making the dataset readily available. Even though we have our own crawler now, commoncrawl has been a huge help in the early stages of development.