@hien-reese +1 for Chrome-style tab grouping.
The code is presumably public and all that needs to happen is to adapt it to Opera's style.
Even with workspaces, it's still handy to have (sub)grouping. I literally have a dozen or more contexts of tabs. I don't want a dozen workspaces. I want to subdivide workspaces into groups of tabs occasionally.
https://blog.google/products/chrome/manage-tabs-with-google-chrome/