An iPad ARC is on the roadmap
There are many older discussion about this. In short, Roon‘s stance was that there were pros and cons both to developing ARC as a separate app and to doing it in one app. For now they decided to develop it separately, but future integration isn’t ruled out.
My guess is that as ARC picks up features, RAAT might be integrated in it, and the final unified app may be ARC-based. However, I suppose that this will need at least feature parity and we aren’t there yet, cf. Focus. And there will be some UI challenges to solve.