f-to-pay-a-visit от Bladt

Follow links and click buttons using the keyboard.
Click the "f" key to activate the plugin, click "Esc" to deactivate.
When active, anything clickable will get a little tag displayed next to it. Type the letters in the tag to click it! Modifier keys (ctrl, win/super, alt) held down while typing the tag letters are honored.

You can escape the extension by hitting "," (comma). If the next key you press is "f" it will not activate the extension.

If you click the "y" and then the "f" key in rapid succession, the selected link will be copied into the clipboard instead of being followed.

There are other extensions that offer similar features, but they seem to always come with a ton of extras, like regex search, or full text-editor implementations.
This extension offers mouse-less link and button clicking/copying, and nothing else.