Non-expert speculation to follow:

Perhaps dunk your plants in a strong solution of saltwater for a few minutes?

That should be really toxic to snails and any eggs with soft membranes. I would think the plants could tolerate that easily for a few minutes (or longer), and then rinse them in freshwater.

Or course, I would try just a few plants first to make sure my suggestion is not toxic to them.

Good luck on your pond vegetation project! Hopefully you can get some actual expert answers in your thread.


P.S. If you have lots of crayfish grazing, you will need to start your plants in "cages" with a small enough mesh size to exclude your aquatic harvesters that wield dual scythes.