This tiling feature looks just like i3 or Sway.. pretty sure it is using it under the hood. Not sure why they changed the default shortcuts though, nor why they want to rename everything under the Pop OS brand.. rather than just give credit to the real contributors.
Its neither i3 nor Sway. Its their own implementation on top of GNOME. i3, sway are too complicated for first time users and requires lot of configuration and tweaks. Personally I found Pop Shell is the best thing that can get anyone started with simple toggle on/off, customisation of shortcuts and available out of the box.