Ive had a side project going for a few years to modularize this exact type of middleware for the browser's WebExtension (and WebAPI) capabilities.

https://github.com/1ps0/elos-connect

https://elos-edu.notion.site/eLOS-Connect-0-0-11-a72acbec893...

Curious to see if anyone else is able to find use cases for the components/sidebar and urlbar CLI I've been building.