Thinking about how to achieve some of these features in Firefox
1. An extension like Tree Style Tabs, but in a dedicated tab, which is pinned to the first tab, so easily accessible with `Alt+1`.
2. A keyboard shortcut for detaching the tab (via something like Tridactyl) and then resizing it using a tiling window manager.
2 is easy to achieve, if 1 does not yet exist in some form I might build it someday.
And I too prefer Firefox with Tree Style Tabs, been using that for years.
In general similar setups are not uncommon on Linux with tiling window managers. Probably the reason this app is available for Mac only. :)
Setting up a nice environment takes time, it doesn't come out of the box. So it is good to see people trying to come up with ready solutions.