I really like persistent ingredients as an alternative win condition too! In general backfire strategies are actually somewhat on the weak side without the inevitable doom of persistent ingredients. If a concoction had a bunch of stuff in it that was meant to clutter up the opponent's pot but it didn't make it backfire before the brew finished, the player may as well have been throwing green slime into the pot to much the same effect. I definitely support adding more persistent ingredients and ways to mess with the opponent, just with some safeguards in place to offer opportunities for counterplay. 50% chance of destruction on backfire sounds like a great solution because it will only occur after the strategy did something, and a half-filled pot is still a large disadvantage for the next brew without being too oppressive. 50% destruction would also be good way to prevent overflow in your own pot with eggplants from virility potions.
I am really happy to hear that you've already got all sorts of plans for upcoming updates, I am definitely looking forward to playing them!