You may be able to get this working using PBP and 2 cables without virtual displays. This is my write up for using HiDPI@120hz for two 57” G9s on my M2 MacBook. https://www.reddit.com/r/ultrawidemasterrace/s/VrBLFDxYzg
┌─┐┌────┐┌─┐
│ ││ ││ │
└─┘└────┘└─┘
Just like the excel world championship I would find a macos ricing/window tiling competition equally enthralling. You read articles like the OP and at some point all you can do is laugh because lord (Cook) knows you've cried.
I like the three-column separate monitor layout because I have hotkeys, primarily driven by my mouse but also usable keyboard-only where I can easily switch between monitors with `⌘+`` which moves my cursor between them. I can select whichever monitor I want and put my mouse to it, and I can switch to any workspace on any monitor quickly. I also have hotkeys that sync three workspace numbers across monitors, so switching between them switches all AeroSpace workspaces on all three monitors simultaneously. If I have five projects going, I'd have the terminal on the left, Linear and other communication tools on the right in accordion mode with AeroSpace, and I can use my mouse or keyboard exclusively to find exactly what I'm looking for almost as fast as I think of it. I spend zero time on window management or organization now so it makes it thoughtless to use.
If I'm just using the monitor's native resolution there's no real way to do portals — having two apps open as sticky and only switching a portion of the monitor space to a different app while keeping the other sticky. There are hacks you can do with AeroSpace, especially since AeroSpace doesn't use native macOS Spaces, but the three-monitor layout is a much more robust approach in my opinion just a bit of a nightmare to setup. Theres a million little mac annoyances you have to fix.