I also trying to come to terms with this, mostly need to design new custom key settings.
Zellij has Lock interface, default Ctrl+G, which you can use and in that mode it only takes that one key, but it's a bit different from how screen works.
I recommend using tmux mode and adding its keybind to locked mode, that way you get the same key interactions as tmux itself. Sadly, zellij doesn't offer the same options for which key that will be (in screen and tmux I like using C-] cause it's usually unused, but you can't use that one in zellij)
Zellij has Lock interface, default Ctrl+G, which you can use and in that mode it only takes that one key, but it's a bit different from how screen works.