Layers are unfortunately not a good fit for alpha-key hypers since they interfere with typing (it's mentioned in the profile's comments, but that's the reason why it shouldn't be used, 'e' is a typing key), you'd better use the principle behind home row mods to turn typing keys into modifiers
https://github.com/gabriel-gardner/modtap-karabiner/blob/mai...
And Keyboard Maestro is better for app launchers since it allows you to hit the same key to return to the previous app (e.g., if you're in a text editor, Caps+F switches to Firefox, Caps+F switches back to the text editor)
You can also create a menu/panel for less frequently used apps which you don't need to remember abbreviations for
I don't think the value-add is worth the cost in general for remembering "start X program". The major OSs have ways of quickly opening a program with keyboard-only input, anyway.
I think with an external keyboard, especially if you can use it with multiple computers, it's worth looking into customising the keymap on the keyboard itself. e.g. if you want to swap the Command and Option keys, keyboards with customisable firmware like QMK will let you do that.
-- My experience has been that if I've had to adjust OS settings to get the keyboard functionality I want, then I end up not using that keyboard functionality.
(Though, if you do go for an external keyboard, I'd recommend going for one where the spacebar is only 1x or 2x keys wide as other keys, not 5x or 6x as wide as the other keys).
What is the cost of remembering that Firefox starts with an F?
And none of the major OSs offer such a convenient way to launch apps
QMK is great, but then it only works with QMK keyboards, while Karabiner and friends work with the rest (also, if I remember correctly, QMK is more limited in the area of rich text input and some other OS integration beyond low-level remapping)
> What is the cost of remembering that Firefox starts with an F?
Collisions and inconsistent mnemonics.
Consider OP's shortcuts for Firefox, Finder, Typora, & iTerm.
OP went with 'f', '\', 'y', and 't'. -- It's more complicated than just "remember the first letter of the app name".
For something as infrequent as "open firefox" (I'm going to open the web browser at the start of my session, & never need to reopen it), it's not worth it.
Whereas, say, "open note taking app" is more likely to be worth assigning such a shortcut to.
> QMK is more limited in the area of rich text input and some other OS integration beyond low-level remapping
Yeah, it generally isn't going to cover OS-specific integration.
Though you can still send keys. e.g. I like using the 'cv' and 'm,' keys for "desktop left" and "desktop right". And that can be achieved with QMK.
> Consider OP's shortcuts for Firefox, Finder, Typora, & iTerm.
Why would you consider them? Make your own and stop at the X number of apps where it becomes confusing. Also, for the top-5 most frequent apps the F=Firefox is irrelevant, you'll remember any combo, so just pick the most convenient (e.g., home row keys), the cost of training the muscle memory is almost none. The infrequent apps can be hidden behind a chord, but then that is best achieved with visual cues (you can use system notifications for that with goku or even better KM app for better UI)
Re. launching Firefox - you've missed the huge part of the switching-to-firefox workflow (it's not just launching the app, the same key switches to an existing app), that is very frequent and definitely worth a shortcut (even though, see my other comment, KM is much better for this task)
And Keyboard Maestro is better for app launchers since it allows you to hit the same key to return to the previous app (e.g., if you're in a text editor, Caps+F switches to Firefox, Caps+F switches back to the text editor)
You can also create a menu/panel for less frequently used apps which you don't need to remember abbreviations for