After serious thinking polygonum_on_google wrote :
Yes, I have seen sets of tools (e.g. 1/2",3/4", 1" and 1 1/4") but they are
far more in terms both of bits and cost than I need.

Is it easy or hard?

20mm galv conduit and it easy to put a thread on it. Not sure what you
intend using it for, so difficult to determine what it should screw
into.