It allows total customization through use of HTML templates and CSS. It's not yet on any extension stores as there is still much to be done but was interested in getting early feedback before submitting. It supports Manifest versions 2 and 3 which means it is both Firefox and Chrome compatible. The code is open source on GitHub and would likely serve as a good starting point for anyone else wanting to build a complex cross-browser extension. There's also a type system that converts Reddit JSON to TypeScript that is still very early stage but again, perhaps useful to someone else working in a similar area.

If you'd like to check it out, there are local installation instructions in the README as well as a starting theme for HackerNews in the templates directory. I'm happy to answer any questions or issues, feel free to open a ticket in GitHub.

Also, if you're interested in contributing, please reach out in GitHub. Cheers!