There are waaaaaaaaaaaaaaaaaaay more things than just sidecut and edge angle that play into the slarve of a turn.
Of course length will play into the pivot as a function of swing weight- in which you will only notice a difference once a ski goes outside your range of comfort and everything below that will all feel the same essentially. Also the camber profile and tip/tail shape will play into how well you're able to pivot slip the ski. If the ski has a square tail and lots of camber it will be infinitely less intuitive in a pivot slip. Conversely, if it is a ski that has not so much camber and a round or twin tail or tail rocker such maneuvers will be a relative breeze.
Sidecut makes very little difference in moves like that specifically because you aren't employing that dimension physically.
For slarving a big turn, it's all in the tips and tails. The way the ski initiates and finishes a turn is mostly dependent on the tips and tails and making a nice smooth slarve will be much more comfortable on a ski that has an upturned or round tail.
As for LiquidFeet's question:
"So to frame this as a question, does rigidity/floppiness of flex, both torsional and longitudinal, mean more than turn radius when comparing riding an edge/carving vs brushing/skidding the skis along the snow in a steered turn?"
Absolutely. The sidecut can be anything, but if the core or layup lacks the rigidity to hold the edges down into that radius then it's all for naught. It's the noodle effect- when you go to drive the tips into a turn and they just sort of fold in half and want to make about a 3m turn instead of the advertised 17m or whatever. You need to match your core materials and layup to the size and intensity of the turn shape it's being mated with for the size of the rider or else you're wasting your time.
Also if the ski is so stiff that your body weight can't really get down into the meat of the turn, it's going to feel shitty and you still won't get the advertised radius either.
At least that's how I see it... It makes sense in my head anyways haha