Full explanation
Hacksaw does not release per-combination probabilities, so a precise "X in a million" figure for a 6-of-a-kind high pay does not exist publicly. Treat any exact number you see with suspicion.
What the structure tells us: a full 6-OAK on a premium symbol across the 6x5 grid is one of the rarer base-game outcomes, since high pays land far less often than the low-pay letters that make up most of the 36.6% hit frequency. Lining up six premiums on a payline is the kind of event you will not see often in a normal session.
Here is the part that actually matters for strategy. In Le Zeus the headline wins do not really come from base-game line hits at all. They come from the Mystery Reveal chains and the Mystery Reels, where Coins, Diamonds, Clover multipliers and the Pot of Gold collect into the large payouts. So even if you could calculate the 6-OAK probability, it would be a footnote next to the feature math.
Short version: rare, unpublished, and not where the money is. Focus on the feature, not the line.
Focus on the feature instead
Chasing an exact 6-of-a-kind probability misses where Le Zeus actually pays. A full premium line is a rare base-game event, and even when it lands it is dwarfed by what the Mystery Reveal chains and the Pot of Gold can collect.
So the practical takeaway flips the question. Rather than asking how often six premiums line up, ask how to be in the game long enough to catch a strong Mystery sequence. Bankroll discipline and a good RTP version do more for your results than any line-win probability, published or not, ever would.
Without a published figure, the practical read is that a full six-of-a-kind on a premium symbol is rare and should be treated as a bonus rather than a plan. Most of your returns will come from shorter combinations and feature reveals. Enjoying the big lines when they appear beats building a session around an outcome you will rarely see.