I came here to ask for "Arc-like split tabs", but I have to admit that Yannick's solution is probably fine for most use cases (and therefore most users).
I'll just add one situation that doesn't solve for: screen-sharing in e.g., Zoom calls. I chair a monthly board meeting in which it is necessary for me to screenshare the meeting agenda and any supporting documents, yet I also need to take notes and such. Thus I only want to screenshare one browser window, not my entire screen. Split tabs (up to 4) works perfectly for this, as I can share that one browser window and trust that board members can see the multiple documents that they need to see in tandem and cannot see anything else. Yannick's solution would require that I screenshare my whole display.
Niche, yes, but hopefully a useful data point.
Meanwhile I do think that Yannick's solution requires some additional UX "help" from the app to get to parity with other browsers' split tabs features. Having to enable focus mode then resize the windows manually is a bit involved, so I wonder if there's a way Orion could shortcut that somehow.
