The Octatrack learning curve is steeper than OP1, but certainly not as difficult as say fluently learning a DAW from scratch, if you will be making loops and sequences in the DAW to replay them as samples in the Octatrack then it could be a nice platform for experimentation and further mangling of those samples. If I was to work like this I’d probably make 1-8 bar loops in the DAW, and make variations and combinations of them in the DAW, render them out, so that you have a bunch of loops to work with. Then I’d probably make some chains* of melodic sounds in the key of your song, some drum chains.
It would be a fair amount of work, probably 1-2 hours to make all those, and load them into the Octatrack, then assign them in the slots/tracks of Octatrack, set fx, then lay out the trigs to create your basic parts probably another 1-2 hours, but then once you have done all of this it can be quite quick to come up with variations using copy/paste, scenes, trig conditions, slot locks, p-locks etc.
*If you want to do melodic sequencing on the Octatrack and are concerned about the limited pitch range of the samples then you can make a chain of pitches then use slices to sequence them, you can use trig mode set to slice to play melodic stuff on the slices, it can be an interesting way of coming up with stuff you might not think to play on a regular keyboard, each slice need not represent linear chromatic pitches, you could even purposely make the chains in a set scale or assign them randomly within a scale to keep it interesting. Of course once you have a chain of even only 12 slices, you can still p-lock pitch and octave, so it isn’t as limiting as it can seem. Just bear in mind that you won’t be able to play more than 1 slice at a time, so for example if you want to do chords make a bunch of chords as the source samples in your chain.