I used to run fluxbox in the early 2000s. I greatly miss tabbing any windows like that.

I believe the Cosmic Desktop from Pop OS has that again

You can run fluxbox today! I still do, I can’t go without window tabs. :^)

There's no equivalent on Wayland?

Sway.

me too! fluxbox and gkrellm for some kick ass desktop "widgets" monitoring the computer :D

KDE had it. And I missed it a lot.

This is what we needed in our OSes instead of Firefox tabs.

How is it that different?

basically every app is a tab. this is how I run i3wm. full screen tabbed layout. smaller modal windows still appear in their normal smaller windows in front of the current full screen app.

Yes the UX is virtually the same

I tried to install a quick VM to answer this exact question but I had some difficult getting it running in Gnome Boxes.