I know this sounds crazy, but has any browser just tried implementing two (or more) horizontal rows of tabs? - the user can decide to put them up the top or on the second row based on their own prioritising. Or just zip them up. Not saying it’s a great idea but these kind of horizontal chrome groups never worked for me, and Arc tabs are too vertical for me.
I would like more a completion based input for search. The address bar can work. but it's usually at a weird place and not configurable (in terms of number of items, labels, and sorting). I would like some command/query popup bar. And then I can reduce the vertical space taken by the tab bar, the toolbar, and the bookmarks menu.