Have you managed to transfer your setup to a different computer?
I know that extensions have unique identifiers, making them easily recognizable online under the same number, and I'm aware of the specific folder where the settings for these extensions are stored. I attempted to copy the entire folder where Vivaldi Standalone is installed, but when I launched it on my laptop, none of the extensions loaded. It seems Vivaldi detected the change of device and removed the extensions. It would have been simpler if it just asked for the main password, but it appears they prefer users to store settings on Google's servers for full control.