I want my Touch Bar to have:
Esc
F1-F12
Toggle Mute
Volume Slider
Screen-Brightness Slider
I don't care if the buttons have to be squished to achieve this. I know you can do some customization through System Preferences > Keyboard > Keyboard, but it doesn't give you much fine control. Is there another interface or maybe even a config file one can use to hyper customize the Touch Bar?
The following options should get your job done
Source is on GitHub. This Youtube video explains it's functionality
Pros: Free and Open Source, More customizations to touch bar than the next option, Adding Custom gestures (Instructions) - It's pretty easy to add custom functionality, All the functions you mentioned: Esc, F1-F12, Toggle Mute, Volume Slider, Screen-Brightness Slider are all there as default presets \
Cons: I had a hard time installing it but type this open -e ~/Library/Application\ Support/MTMR/items.json in the terminal and then you should be good, My friends complain it's buggy in Big Sur but I haven't upgraded yet so no opinions on that.
Pros: Completly customize the touch bar just like the above app, Wide range of gesture controls for Apple peripheral such as Magic Mouse and Keyboard, Big Sur Native Compatibility.
Cons: It's paid 😒, Text Triggers are quite buggy.
I use BetterTouchTool cause it has more customizations for the Magic Mouse and Keyboard but for your requirements, MTMR should do the job in flying colors.
MTMR , it's free but it does need some editing to get it fully customized
