However I'm not sure Swish solves the big benefit of i3/bspwm for me, which is the lightning-quick virtual desktop and "send to desktop" functionality of a tiling WM on linux. Having two apps open side by side is useful, but not quite as useful as having two apps open full screen on virtual desktops 1 and 2, and the switch between them being totally instantaneous.
I recall that yabai can achieve this with SIP disabled. It somehow injects code to disable the Space switching animation, so hotkeys to switch Spaces become instant.
Have you ever heard of Phoenix? https://github.com/kasper/phoenix/. Despite googling around for this exact topic, with 3.8k stars I had never heard of it. Apparently someone has created slim, JS scriptable interface that is basically tailor made toward creating your own tiling WM. I just installed it and loaded one of the examples: https://github.com/nik3daz/spin2win. And what it does is basically ignores the built-in spaces and creates truly virtual desktops by just hiding and resizing windows. And it works pretty well. The response time between switching "desktops" is basically instant.
I'll admit it is a little bit janky (which the author admits/warns about). But it seriously does work better than yabai. This config (using Phoenix) basically abandons the native "Spaces" functionality and does everything by just maintaining an internal window state and moving windows around fast. So you don't have to disable SIP (a big thing for me, since I want to use this at work). I'm seriously kind of blown away, this is miles better than apps that people are paying for, and it was just sitting here in this guy's github fork.
It is super disappointing this is the best that Mac can do though. There is no reason there shouldn't be a mostly-native (ie, less janky) tiling wm solution on the platform.