Disinfecting plants is usually done with things like (dilute) bleach, hydrogen peroxide, potassium permanganate, alum, etc.
However, as you are going to leave it in a separate container (with no other fish) for 2 weeks, any piscine parasites/diseases should be eliminated (as they have no host).
However, that being said, your goldfish may well eat whatever plants you throw at it!
I am getting ready to plant my first tank this weekend. I was originally hoping to be able to do 100% tissue cultures, but between supply chain issues and wanting some plants that I haven't seen as cultures, I'm on a mostly farmed path now that runs some introduction risks.
I wasn't planning on adding fish for a while until the tank was stabilized somewhat, so this is less about piscine parasites/diseases as it is about snails in particular. I just really don't want any for now and when/if I do, I want to be specific. I'd also like to avoid the regular run of other bugs and parasites that will probably be hitching a ride.
That being said, I have on hand and am comfortable with potassium permanganate as I use it for my koi/pond for occasional issues (just on a much much much larger scale at 3000 gallons or as a concentrated dip) My koi pond is not planted, so I have never had a concern with plants before.
A new fish koi dip is 200ppm for about 90 seconds while a whole pond treatment is about 4ppm for 8 hours.
Does anybody have experience with PP dips/treatments for new plants?
I assume some plants are much more sensitive than others and there may not be a lot of knowledge there. My gut tells me mosses would be on the sensitive side because of how delicate they are as well as anything else with more delicate stem or leaf structure, but I honestly don't know. I do know that PP consumes all the algae it touches and after neutralizing with H2O2 or Sodium Thiosulfate, my pond water is gin clear for a while.