Safari's Tab Overview is unfortunately not like the OP's idea. The lack of dragging, and also because there's no way to zoom out further and make visual groups. And I suppose being horribly slow with many tabs makes it very different from the OP's idea too.
I also found Tab Overview is a disaster if you have too many tabs. I've occasionally been looking at Google Maps and done pinch-to-zoom-out. Big mistake: Safari zoomed out of the page instead and tried to show Tab Overview. That scheduling loading every tab that was previously in a sleeping state, just to show the thumbnails, and would typically show as using 30-40GB memory while I realised I'd have to kill and restart the Safari process to get back to work.
I like Safari, and switched to it from Firefox because Firefox was getting very slow. (Turned out to be the Tree Style Tabs extension, not Firefox itself).
But it eventually I found Safari is good at seeming fast while using a huge amount of memory that slows down everything else on the system. It was not unusual to find Safari using a lot of swap and increasing over time, and being the reason other things I use for work were getting slow.
I switched back to Firefox and found, rather pleasantly, its memory use rarely shows higher than about 10GB.