dotfiles VS qmk_keymap

I'm a full-time Angular developer who has used vim for a decade. You can find my dotfiles here and in particular my Neovim setup.

On top of learning the keyboard and finding a good layout, I had to make (again - see a trend?) hundreds of small tweaks to application configurations.

That's extremely reductive. I rely on the OS for the language support, just like I rely on the OS to understand the USB protocol. It's an inherent part of how a keyboard works. I use tons of other mapping features that are best implemented keyboard-side, including but not limited to:

I hate having to wait for any delays, so I prefer using explicit layer-switching keys, and have configured things so that I'm never tripped up by a timeout or whatever. https://github.com/henrebotha/qmk_keymap

You'll need one or more variables to track things like when you pressed the key. See my map for an example of how to do timing-based stuff using a custom keycode. My use case is quite different to yours (though it's incidentally also related to task-switching!), but you should be able to see how I check for my custom keycode, how to record the time at which something should happen, etc. (Search the file for mentions of KC_TASK.)

I implemented a Tmux layer that automatically prepends the Tmux prefix before every key. It saves one keystroke if you do a single Tmux command, and 2N+1 for N consecutive Tmux commands. https://github.com/henrebotha/qmk_keymap