You can read it just as an inspiration. Getting HN to Kindle would be fairly simple - just use a script to download it, basic formatting, convert to mobi and send to email (though OP apparently supports also some kind of category classification, which might not be so simple to set up). But for 5 bucks for lifetime, without needing to have a machine running...

Replicating the obsidian plug-in functionality to suit your own note/knowledge management app would be probably even easier.

What I don't like is the tagging part - kindles are terrible to type in. And if you want to avoid it by using your phone/tablet, you'd be better to avoid kindle app altogether and do the note taking using browser extension or something.