I would follow that Vivaldi team to the ends of the Earth, as nobody ever made a better browser in my opinion then they did with those last versions of Opera before they had to sell (versions 11 or 12 I want to say). But for one thing, which is that Vivaldi is unfortunately also a Chromium based browser.

Which means among other things that they didn't have the capacity to sustain manifest v2 while Google pushed the browser into v3. And some version of that will be true when Google starts pushing, say, mandatory sign in, or AI powered DRM enforcement, or hard coded browser level warnings to comply with the law if you visit Anna's Archive, or limit your search engines to "safe" search providers from a list provided by Google, or using your location to determine if you're in a jurisdiction that has banned certain xxx sites.

Love the team, but the world isn't fair. They are the example I keep coming back to whenever I hear people say "Mozilla should focus on the browser!" (as if they don't). Opera is your perfect natural experiment in demonstrating that success is driven much more by distribution monopolies. If focusing on the browser and delivering best in class performance and focusing on core features your users most wanted were the things that delivered market share we would all be using Opera right now and they never would have had to sell.