Niri works fine on multiple screens, you can configure it pretty well. AFAIK it does not let you drag whole workspaces onto a screen – each screen has its own scroll of windows and set of workspaces, and you can move windows between them, but not move whole workspaces.

Came here to say this. Simply the most intuitive way to interact with a computer.

I have KDE installed as a backup, and use the whole KDE software suite, but Niri is GOATed. Especially since KDE trackpad gestures are so terrible.