I'm on wayland. Kitty can be used as a layershell window. So you can build panels, taskbars, etc if you were so inclined. For example, you want fastfetch or htop as a live desktop background? Kitty can do that.
To be fair, "more consistent" if you only use KDE apps. Once you start adding other Linux apps, you end up with a motley crue of GTK 3, GTK 4, QT 5, QT 6, Electron apps with some dark, some light and everywhere in between. Consistency doesn't exist on any OS.
As someone who spends most of his time in nvim and TUIs (yazi, lazydocker, termusic, tmux in ssh ...), Niri is as keyboard centric as you want. Mine is configured to use vim keys.
Tilers can remove Gnome's overly whitespaced decorations, probably saving 10% in screen pixels alone.
If you want to maximize all windows on run, niri can do that with a rule. It then becomes like a monocle layout where you can use swipes/keyboard/scroll wheel to navigate between maximized windows. I don't know of any DE that will run all windows maximized by default.
Too bad I no longer have an 800x600 netbook. Niri would be perfect for it.
Niri doesn't use 400MB by itself, that's the entire memory footprint of everything running. In comparison, OpenBox with all the utilities needed for wallet, ssh agent etc is in the 450MB range on my box. That's probably due X11 vs Wayland.
A minimal Niri functional environment is similar to IceWM in RAM usage. I used to run antiX in VMs.
Niri is RAM efficient. I run Niri in an 8GB VM on Intel Macbook, and on a $99 8GB mini PC. Total RAM usage on boot is less than 400MB with waybar, polkit, ssh-agent, mako ... That's in the ultra lightweight WM category. Compare that to Gnome+paperwm (1.6GB)
There are features Niri sorely needs: 1) 2D overview (zoom in/out), 2) enhanced meta for windows (to create window indicator [1] and window picker)
Many editing operations involving the the mouse can be reduced to a few key strokes in Vim and become second nature. As an example, how many coders reach for the mouse when they cut text in "modern" editors? I don't think they need to be convinced Ctrl+X/Cmd+X is faster than the mouse.
If you want something lightweight and based off of Ubuntu, go with Xubuntu. It's more like Windows 95. I do not think it's the trendiest but it's been a stable workhorse for software development. Xubuntu is fast on older machines and virtual machines. I was turned off by the main Ubuntu distro a while ago as it baked Amazon search and other commercial offerings into the desktop environment. (I don't fault them for trying to make money but it should have been opt-in)