I thought Sway was based on i3, which is an arbitrary-width tree that can have different display modes per container node in the tree.

Hyperland's wiki only lists "Dwindle" and "Master" layouts, which from the description are strictly less versatile than i3 (and Sway?) in exchange for convenience if those layouts are what you want. Does it even have something as flexible as i3? (and Sway?)

I use the dwindle layout which is similar to bspwm in automatic splitting mode. One advantage is you can drag and drop windows into other nodes, which will be split appropriately, it's surprisingly neat when you have a lot of stuff open. It's easiest to get a feel for the differences by just trying it out or watching some videos of it on r/unixporn