Before Microsoft even announced their windows as tabs feature, "Sets", Stardock had released Groupy v1.0.
Groupy is pretty straight forward: We like having our browser windows organized by tabs, why not the rest of the OS experience?
There are a number of popular use cases for Groupy. For instance, merging multiple Windows explorer windows together with tabs the top.
Groupy supports Windows dark mode
I find it particularly helpful that I can just click the + button to get another tab.
Here's how I use Groupy when doing development work. I have GalCiv and Siege of Centauri and Perforce grouped together. This is my "Dev" app.
I like to think of each of my groups as an "App" in itself. That is, if I treat Chrome as a single app with lots of tabs for different pages, then my Dev "app" simply has tabs that let me switch between different tasks related to development.
You can try Groupy for yourself at http://www.stardock.com/products/groupy/. I suspect you'll find it as easy to use as I do.