@TritTriton @user365 @Vivaldi, the small part of the code which is proprietary, but full auditable is the part related to the UI, nothing relevant to the privacy feature, but Chrome and EDGE are very hungry to this part, if they could fork it it would be the end of Vivaldi and all other Chromium browsers.
For Firefox and forks it is easy to be OpenSource, because there isn't any big corporation which use ore made Gecko browsers, not so with Chromiums as by far the most used and used also as base for the worst Data hogs out there.
Vivaldi as the only relevant EU browser and also the most advanced and feature rich existing one, need to protect more than others it's unique features and souvereign against the big global players, for the own existence and the one of others, in a brutal market of almost 100 different browsers and othe 70 which had already lost the battle.
Because this it's pretty irrelevant currently, if a browser is 100% OpenSource or only an 96%, there are more important other points, like the community, the ethics and transparency of the company.