Collectively, of the known abilities? I'm sure it's extensive.
Potentially unknown abilities of Haki that he doesn't yet possess?
- I would wager that everyone who currently uses Haki is on a lower level than people who used Ancient Haki abilities. So, there is an entire other category he hasn't even scratched the surface of yet.
- Beyond the Ancient Haki abilities, I believe there may be unknown God level Haki abilities that nobody has ever used.
So... I would say Luffy hasn't learned a ton of skills that he could be using both known and unknown.