Not that useful
A UToK sounds useful but it's not really. Many software systems do not allow maximally flexible keybindings. Often they have other keybindings in place of your preferred one. Worst of all it is often easiest to simply use the default keybindings because the hassle of forcing your UToK onto a system isn't worth the effort.
Tools that I use that support most of my UToK: Ghostty, Zed, Vim.
Nice to have a goal
Still, it's nice to have a goal.
Also, when setting up these keybindings, I like to be minimally destructive. Ideally the software system I'm using allows me to create this binding alongside the default binding.
Keybindings / keymaps
Heavily inspired by Vim and Zed. I aim to be as ignorant of context as possible. A "thing" can be a pane/window/buffer/tab/etc.
shift-esc : expand / zoom (e.g., full screen active thing)
ctrl-esc : quick / quake (e.g., quick terminal)
cmd-w : close
cmd-t : create tab
ctrl-w v & alt-v : split vertically (to the right)
ctrl-w s & alt-s : split horizontally (to the bottom)
ctrl-w = & alt-e & alt-= : equalize things
ctrl-tab : move focus next (tab)
ctrl-w w & atl-tab : go next (non-tab)
ctrl-shift-tab : move focus previous (tab)
ctrl-w shift-w & alt-shift-tab : move focus previous (non-tab)
ctrl-w h & alt-h : move focus left
ctrl-w j & alt-j : move focus down
ctrl-w k & alt-k : move focus up
ctrl-w l & alt-l : move focus right