How can I have unlimited keyboard shortcuts? There's only so many keys in a keyboard, I want limitless
possibilities with key bindings by being able to bind key sequences
to actions.

How can I bind an action to an extended shortcut?

Let's say

Control-x-k to    'open textedit'


I know there's no hardware limitation preventing long keyboard shortcuts, because with emacs you can do

(global-set-key (kbd "C-x k") 'open-something)


ref
I don't believe that macOS will let you add key sequences in System Preference -> Keyboard -> Shortcuts. However, you should be able to do it, but you will most likely have to manually add shortcuts in plist files.

I think the answer provided here, as well as this repository, will help you create custom keyboard shortcuts.

You can also check out Keyboard Maestro's FAQ on their workarounds to key sequence shortcuts.