This one, obviously really-good-feature is still not implemented in Opera. There are several articles on the web about using selecting and dragging groups of tabs - or saving groups of tabs to a bookmark folder - but in every case Opera was not on the list in the how-to article. (An example: https://www.makeuseof.com/bookmark-all-tabs-chrome-firefox-edge-brave-safari/) I really like Opera but the one most annoying thing missing in Opera is the ability to select groups of tabs to bookmark into a single folder (and, of course, subsequently dragging bookmark folders around at will later which Opera DOES support). Without this one bookmark function I am going to, sadly, have to pass on further use of Opera. Since the original post on this topic was way back in 2017, maybe I will re-visit Opera every few years to see if the function has been implemented or not.