Vivaldi has a setting for this in vivaldi://settings/appearance/. It's the "Menu icon style" setting. The choices are "Vivaldi icon" (where it just has a V icon with no text, but a tooltip that says "Menu" on hover) and "Menu icon", with the latter meaning the hamburger icon.
It's really nice to have that option. I set it to "Menu icon". Would indeed be great if Opera had it too, but with an addition "No icon" option to solve your case.