I am not sure what you mean by "chemical finishes," but here are some discussions about the subject:

Walnut countertops

Food safe finishes

And some information on tung oil

below

Here is a link that might be useful: Walnut countertops

VERY helpful! Thank you!

Walnut oil does NOT harden into an actual film.
Tung oil WILL harden and form a film.

Non-film finishes look better when chopping and cutting may occur on the surface.
They are easily repaired by simply applying another coat when the surface starts to look worn.

Film forming finishes provide a higher degree or protection from stains and damage within the limits of the finish, but must often be removed (or at least sanded) before applying a new coat.

Almost EVERY finish is 'food safe' after it cures.

"Walnut oil does NOT harden into an actual film."

Not completely true. Walnut cooking oil will not harden into a film - like any other cooking oil.

Polymerized walnut oil will harden into a film just like tung oil or any other polyermized oil. I use polymerized walnut oil on cutting boards. You need to flood the surface and continue applying the oil over a 20-30 minute period and then wipe off the excess.

The oil will penetrate the surface and then harden at the final depth it has penetrated. Like any other polymerized oil, this forms the base for the subsequent coats.

Reapply the same way another 2-3 times with at least 1-day between applications and you will have a nicely sealed surface.

You can wipe the surface with soap and water to clean it, and then just follow up with another light coat of oil.

We have a butcher block that has been treated like this for the past 6 years and has a beautiful surface.