@leocg No what I'm comparing is how successful one implementation of the feature is to one another. If you were to compare GX and Vivaldi then yes doesn't make sense since GX is a niche browser.
For example for speeddials I compare Vivaldi, Opera, Yandex, similar feature. there All three are somewhat equal.
Pop-up compare with Yandex similar feature. Yandex's is more polished, supports keyboard naviagtion, and auto-pop up. If it can be done and is better to have it than not to have it then is should be done.
For statusbar you can compare any browser that has it. Look at it's implementation in this case Vivaldi has managed to make it relevant and useful again by adding feature rich things to it.
Sidepanel - Vivaldi managed to add rich features to it to make it relevant and useful. Opera, Yandex not so much. And Opera has been trying the sidepanel for a long long time now and still fails.
It doesn't make sense to not compare it as they try to be an alternative to Chrome, Vivaldi wants to be personalizeable. Opera wants what? it's actually not very clear what it wants to be given the direction of where the browser is going. Wants to be privacy oriented? then compare privacy features to Epic, Brave, Firefox. Compare similar features to browser that have the feature as well.