The extension is deadass simple and is basically a userscript that can be configured by chrome's shortcuts system.
For now it can: - like/dislike/unlike the video; - press subscribe button (auto confirm unsubscription as well); - change notification bell status (all/personalized/none).
Missing a feature? You can create an issue and request it. See its github page for more info: https://github.com/NFrid/yt-shortcuts