I switched from Tmux to Zellij ~2 months ago. What I like most about it is the floating panes feature that makes it really easy to create terminals for running stuff in the background without taking up space in the main window.
If I want to run something in background, I just Cmd+number to another window and run it there. Thanks to multiple panes & windows, I can have N things running “in background”, it takes a millisecond to switch to any of them, and I guess if I bother I could even have window tab title reflect the status of the process.
I’ve seen floating windows in Neovim, but I see only one use for them: expanded LSP error messages. Otherwise, I use floaters when they come plugin’s config, but they are more of a nuisance and are tricky to manage without resorting to pointer device.
The benefit is that you can only use one window for every project instead of 2 or more.
What I usually do is have Vim take up the entire window and use floating terminals for background stuff which can be brought in and out of view with a hot key.
The floating terminals are stacked by default, but they can also be arranged side by side if needed.
I won't claim it to be a huge game-changer for productivity, but its definitely a nicer workflow for me.
I keep different Tmux instances for different projects so I get up to 9 windows per project with no overhead.
What I'm talking about is this: https://imgur.com/lUvhjJe
The 3 floating windows above a Vim instance
Also in tmux you can just attach a existing window as a split to your current window and then pop it out again using aliases/bindings.