forgot to reply to this - it could be done but the big question is how would it work? one way could be recording a pattern while you have an external clock plugged in, so in addition to notes it would record the phase relationship relative to the clock and then somehow preserve it during playback. this would be difficult to implement, and not sure it would provide satisfactory results anyway. a simpler approach could be simply treating the ext clock as pattern start and stretching/shrinking a recorded pattern to that.
the easiest option might be adding runes for small speed adjustments (i think this will be very useful regardless), and using ext trigger not to clock but as a pattern reset. so, record with whatever feel you want to have, then sync pattern playback to ext trigger and adjust speed to taste.
polyearthsea will run on any of the trilogy modules (white whale, earthsea, meadowphysics) or ansible. if youāre not planning to use i2c then the obvious deciding factor is what outputs are more important to you (CV or gates).