I was struggling to get the extension to show up in "Extensions" application.

That's because when running npm run build and npm run linkdist, a symlink to dist is created as shown in the image below BUT the dist files need to put into this directory directly like shown too:

Long story short: instead of symlinking the dist folder over as a whole, it might be better to just copy the contents of the dist folder over and overwrite any files already existing in the extensions directory.