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Bactericides and fungicides, often, overlap. Anything that contains copper will be very effective, but there are natural fungicides as well.

These articles will help:

https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm

https://www.gardeningknowhow.com/special/organic/biofungicide-information.htm

https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm

Here is an article that will help you with the care of Spider Plants:

https://www.gardeningknowhow.com/houseplants/spider-plant/spider-plant-care-gardening-tips-for-spider-plants.htm

Three teaspoons of water to one teaspoon three percent peroxide will be appropriate if you are using this as a way to remove soil contamination. Generally, I use one part peroxide to three parts water. You can go as diluted at one part peroxide to ten parts water and still be effective, though.

Here is an article that will help you with its use:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/using-hydrogen-peroxide-in-garden.htm

That is a very strict set of conditions! I can't think of anything that will do well in that, particular, spot. Your local extension service may be of assistance, but there may not be much of an option, here.

This link will help you to find the closest extension service to you:

https://www.gardeningknowhow.com/extension-search

This article will suggest plants that are Juglone tolerant, which will be your biggest obstacle:

https://www.gardeningknowhow.com/edible/nut-trees/black-walnut/black-walnut-compatible-plants.htm

Paraquat is said to adhere to soil particles for many years but in an immobile state. It is supposed to only be used by licensed applicators.

This article should help:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-long-does-weed-killer-last-in-the-soil.htm

As you can see on this table, this ingredient is not labeled for use around vegetables. https://www.uaex.edu/publications/pdf/_P%20Homeowner%20Insecticide%20Product%20List.pdf
There are quite a few safe alternatives, like this one: https://www.gardeningknowhow.com/special/organic/cornmeal-in-the-garden.htm

As to any lasting effects, it would be best to contact the manufacturer to learn how to remove any residual substances from your vegetable garden. It may not be necessary, but I would certainly check with them before planting in the same soil.

In many areas it's illegal to bury pets in the backyard. I can't find any reputable source that says it's OK to eat fruit from a nearby tree. If the rabbits died of disease or were euthanized, it may be of concern. If they died naturally, it is likely fine. You may want to consult a local agricultural group or university. Even a veterinarian might know.

You might find this interesting:
https://www.gardeningknowhow.com/garden-how-to/info/is-there-a-safe-way-to-bury-ashes.htm