I have a layer for mouse movement with wasd. On the same layer, I've bound hjkl to the arrow keys, so I can get vimish movement wherever. Below these keys on the same layer I have some browser navigation shortcuts.
I use evil-mode in Emacs. The key below my left thumb is control on hold, escape on tap, and it works beautifully. On my left thumb cluster, I have a key that's option (meta in Emacs land) on hold, and option-x on tap (so I can easily hit M-x in Emacs).
On another layer I have hotkeys to manage window tiling. I use Magnet for macOS; works fine for my needs. One thing I wanted that Magnet didn't have was a half-width-but-centered hotkey; I was able to build that into a macro on my keyboard.
Keyboard macros are a beautiful thing. QMK firmware is the best!
My layout: https://configure.zsa.io/moonlander/layouts/xK7zR/latest/0