Bookmark sync should be provided by an add-on (so that it can sync cross-browser as well). There's Xmarks and given that Vivaldi has some compatibility with Chr

Bookmark sync should be provided by an add-on (so that it can sync cross-browser as well). There's Xmarks and given that Vivaldi has some compatibility with Chrome Addons, this should work (if it doesn't, improving addon compat should be top priority).