Visual organizational tools are very important to me. Even if I'm in the IDE and thinking in code, when I jump tot eh browser for something I want the experience to visual and low-friction, so I don't have to push brower things onto my mental stack, which will slow me down when I want to switch back to the IDE.
I'm very good at remembering where things are, I can pick up a book I haven't touched in months and remember the page I was on, or the last sentence I read to find my place with a few seconds. On the other hand, large scale sorting and rearranging tasks are miserable drudgery so I have a lot of stacks and my bookshelves are, ah, suboptimal.
That, combined with relatively small units of work (most of my kanban cards are in the 0.25-2.0 day range) means that I can just go on tab closing sprees frequently.
I ended up liking this approach because having a zillion open tabs introduces a subtle stress and anxiety that's sort of like when I visit a hoarder.
Sort of like when I'm being a hoarder, for me... :-( Gotta try and learn something like your approach. (I'll do that as soon as I can get around to it, i.e. when I'm done with all the procrastinating that's piling up on my to-do lists.)
On any Ubuntu/debian system this is pretty trivial try using apt install. You've i3 which is an old popular program with a big community. You use it with scripts like dmenu. It's definitely more of a "hacker" setup that your parents probably aren't going to want to use, but if what you are doing is focusing on a few documents, it's hard to beat. It's a lot more complete than floating single windows over your pane of code. The Bonsai implementation is slow in comparison.
There are lots of others like bspwm (even more hardcore), but my favorite anyone can use this tiling window manager is easily pop_os's from System76. When I have to use Windows or Mac and I don't have that functionality it is annoying.
https://www.youtube.com/watch?v=UUrvF0Y9AUg
This functionality really should just be built into the OS. The mac equivalent hacks have slowly gotten incorporated into official releases over the years (side by side windows), but they seem to pop up and then die, like Spectacle. If these guys want to do more than just browser documents, what they've got to build is essentially a cross platform tiling window manager. Not easy.
I think the closest you could come to hacking this together is with qtile (py) and you could get pretty close functionality wise.
I've been using Rectangle for ~1.5 years now, and it's been pretty stable and gets regular updates and patches.
The big concern I would have if I were these guys is their magic is their UI, apparently, and they've given it away. If they truly have something good, it's some Electron windows inside a gui kit. Not to understate the work, but the work is ahead of them, too.