This is a Firefox/Chromium addon that has yet to be signed. Tested on Firefox 87.0 Tested on Chrome 89.0.4389.114
You will need NodeJs
Run npm i to install al the required modules.
Run npm run build to build the app. Then use your browser of choice and load the ./dist directory as an unsigned addon/extension.
Run npm run debug to build with all JavaScript map file for debugging, alternatively use npm run watch to build a debug version when file changes in the ./src directory are detected.