I use this cheap Logitech
with an iPad Pro, works fine, pairs instantly.
Standard disclaimer about iPad Pro: I think it is an awesome device, if you use it in a way that takes advantage of its tablet features. If you're not using it primarily in tablet mode (and taking advantage of the stylus), I think there are cheaper and better ways to get the job done. Namely, if they switch to a windows tablet/ 2-in-1, they get a full-fat MSFT Office package. I wonder if you can still pick up a non-pro Surface 3 somewhere, that would be my ideal for a light tablet that I could plop down and do some more serious word processing on when needed.