I agree that elite skis / k1's improve balance, because balance is learned skill and not just innate reflex. Yes, there is such a thing as innate balance, but I would describe that as merely the first rung on the balance ladder. Some gifted ones get to start on the second or even the third rung if they are a generational talent... but no one starts on the top.
So how to actually do it? Progression. Moving to a more demanding craft at the right time / place is a crucial tool for continuing to progress those balance skills and climb the development ladder until it's feasible (maybe not always wise) to paddle an elite in ski in damn near anything.
There are a matrix of assets and liabilities that factor in progression to take place safely. Just hopping in a demanding boat needs to be done carefully and in consideration of what the end goal is vs the resources to actually get there. Our sport is very unique in that there is such a fine line between "I'm having the best day of my life!" and "Oh shit, this might be the last day of my life..." Things that I personally believe need to factor in balance progression; physical fitness, psychology, risk tolerance, safety measures and exposure.
There may be others, but those are top of mind. The last one; exposure is the key. It isn't just bucket time, but intentional bucket time. Drills. Critique. Variation of conditions that combine to make a personal catalogue of experience, knowledge, wisdom and capability. It's unique for elite or even highly developed paddlers to be surprised on the water. It does happen however, and when it does it can be lethal because that may involve a degree of exposure that excludes immediate rescue (I personally nearly perished attempting to solo the West Coast of Vancouver Island in some truly heinous conditions and gear failure).
I'm going to pivot to something controversial now and say that I am NOT in the zero feather camp. Having worked with paddlers who have attempted this approach, I have noticed nearly universally sloppy catch and a host of connection issues related to a general lack of core engagement (no tripod). I am of the opinion that it prioritizes bracing above actually paddling, and while well intended, is a crutch that ultimately interferes with paddler progression. Zero feather paddlers progress more slowly, paddle more slowly and have to unlearn very bad habits later; ironically including learning dynamic bracing (bracing to catch described in my first post). While I am not a fan of arguments from authority, I don't know of a single elite / pro racer using zero feather today, and it's not because they haven't tried it or were simply taught another way. If something can produce even a decimal point of improvement, they'll do it. I've personally experimented with it, and recorded my data. I am far more biomechanically efficient at 62º feather than I am even 45º. It drops off a cliff at 40º and beyond to zero. End rant.