Consider that chrome is now adding a split pane too. So you have tabs, tab groups, vertical split.. surely soon they'll add horizontal split and you'll have a full tmux or a tiling window manager within chrome

Shouldn't that just be your OS? It should show a list of open windows, allow you to group them and switch between windows within a group, show side by side etc

But like, once you start using a better window manager (as exist on Linux for X11), maybe you would no longer be able to imagine working in a window that couldn't simultaneously mix tabs from different apps.