No, not many companies are approved by CASA in the sentence that reads "or approved in writing" in CAR233. Jeppesen, Lido and Airservices are.
Yes it seems odd as the documents are sourced from Airservices however they are processes into a different format for use, for example maps are warped into Mercator (from Lambert Conformal Conic) which changes some things like a straight line is a Rhumb line instead of great circle. DAPS are converted to JPG from PDF to display quicker.
The other issue is for example if somebody got the coordinates for BLACK IFR waypoint from OzRunways and put manually into their FMS, CASA hasn't certified that we have properly stored that waypoint data to sufficient standard. For example somebody might cheap out on database storage by storing that as a 16 bit float which may cause rounding errors thus changing the position slightly (yes for you geeks, we use 64 bit doubles so there is no problems). This kind of thing was probably more of an issue in old aircraft computers where space is an issue, but not any more.
So take the stuff you need under CAR233 and your iPad can be a safety enhancer by offering all the extra info you normally wouldn't have available.