Have just been trying Midi Designer Pro 2 on iPad. Great so far
There’s even a quite evolved Octatrack template up on the ‘community’ section that some kind person is sharing for free/donation 
Great to finally have 8 faders right there for track volumes and of course all the possibilities beyond that.
I’m actually happier stabbing at an iPad screen than the precious trig buttons on my OT so there’s that too!