This will be an intriguing one to follow. I know from years of
enameling that Thompson Enamels does not vouch enamels safe for use
with food. This is because they’d have to test each individual
color, due to the various pigments, or oxides used in each, and that
would be prohibitively expensive. Many of these oxides are toxic,
and could be leached out of fired enamel by acidic foods. Same for
the use of wine or orange juice in lead crystal for instance.
However, there is commercial enamel ware, popular again, that is
cookware, but would those companies help an individual? I have no
answers, only more questions I guess. Good luck!