Can we add additional key presses on our IVR Menu?

I mean, I think there might be cleaner ways to do it. If you're using more than 10 options you might be getting a bit complex. You can always announce the key press and set a queue/ivr/extension as that key press.

So, say you want there to be "key press 10" and you want it to route to "sales queue" - create the queue, assign it as 10, and announce that in your menu. The client/inbound caller won't know any different. The only complexity will be for you to manage it, but even then it's not that bad. Realistically, I'd suggest using sub-menus to split up your options and handle inbound calls a bit cleaner.