Looks like the only thing missing is the shortcuts to select URLs to follow on the current page (which is pretty cool, btw).

Otherwise you can do everything Vimium can by customising keyboards shortcuts and using the "Quick Commands" menu (similar function as the menu brought up when typing "O" in Vimium).

Keyboard Shortcuts settings: vivaldi://settings/keyboard/

Quick Commands menu: https://help.vivaldi.com/article/quick-commands-menu/