This is me exactly haha. What I really want is just gnome with a little more tiling capability for the rare occasion, like thirds and quarters. But the majority of my tiling needs are in the terminal and tmux is the hero
PaperWM is almost exactly what Niri is in a Gnome extension form. It might actually also be the first to implement that kind of workflow.
https://github.com/paperwm/PaperWM
They follow ubuntu releases, kind of. The downside, they went all in into their new desktop env - cosmic, and until they release it they won't move on from 20.04..
I really loved the tiling feature in PopOS 20.04 which came out of the box. But then I bought a new laptop, and had to move to arch to use it..
Tiling Assistant might be worth a try. It can be configured to be pretty out of the way and just add more snapping sizes, different per-monitor if you need.
I only use tiling when I'm coding, so I have a shortcut to a script that tiles all the open windows and gives the main window around 60% of the screen width.