You can do a lot with the built-in key mapping and the default ableton shortcuts, but I'd really love to be able to make shortcuts for ANYTHING, sort of the way you can automate an entire series of actions in a web browser with selenium (https://www.seleniumhq.org/).
For example, I'd love to create a shortcut for adding Saturator to the currently highlighted track in arrangement view. Then I could make another shortcut for adding Glue Compressor to the highlighted track, and another one for some third party plugin. I use a lot of the same plugins on different tracks, and I like doing it that way instead of using sends because I like being able to dial in different settings for each plugin on each track.
A lot of my projects are pretty sound design-heavy with tons of tracks, so this would save a ton of time not having to click through menus and drag instances of plugins to my track every time.