This just seems a rather odd request/suggestion, IMO. Vivaldi is ok as a browser, but i don't need it extensible to also control my washing machine & toaster, et al [Vivaldi does Skynet]. As for our desktops, we already have such wondrous choices.
In that os, you could add side web panel where you could keep applications
In all the mainline DE's i've used, sans-GNOME, it is trivial to create additional panels, &/or docks, for holding standard & custom app launchers.