I wanted to make one for Vivaldi but it doesn't use Chromium bookmarks API and there was a discussion about it already where it was said to be implemented with

I wanted to make one for Vivaldi but it doesn't use Chromium bookmarks API and there was a discussion about it already where it was said to be implemented with the option to sync on a self-hosted server. (https://forum.vivaldi.net/topic/5816/sync-settings-and-bookmarks https://forum.vivaldi.net/topic/5816/sync-settings-and-bookm...) I've also been working on one for Chrome but haven't had time lately to work on it.