[kuerbel]

In Germany there is a thermal paper that is considered food contact safe

https://www.koehlerpaper.com/en/products/Thermal-paper/TH_Bl...

Maybe someone sells this where you live? I have found a shop in the US: https://www.ncco.com/blue4est/

Searching for blue4est was the key.

[V__]

I just checked and there is even a seller on Amazon delivering in the U.S., so it shouldn't be too hard to get.