Edit: my bad, seems like I misunderstood. PopOS used/is still using GNOME and has a Auto-Tiling plugin that behaves like i3wm (?). I guess this is what OP is talking about!

Not entirely sure what you mean. PopOS, developed by System76, uses the Cosmic DE, which is itself also developed by System76.

River is a dynamic tiling WM which is known for it's customizability among Wayland WMs, as it doesn't distinguish itself with it's "layout generator" (though it does come with a very basic one), but instead let's the user write their own or use an existing, third-party one. This way you can achieve essentially any dynamic tiling behavior with River.

How does PopOS use a system like that? Or do you mean that Cosmic is DWM-style, i.e., dynamic and with tags?

I do agree that River is wonderful though!