Is writing the Beautiful Names of Allah on rice or carving them on fruit considered a waste of Allah's blessings, or is it permissible?

There is no objection to writing on rice if what is written is permissible and it is preserved. If what is written is one of the names of Allah the Almighty, then it must be glorified and protected from desecration. As for carving the names of Allah the Almighty on watermelons or eating rice on which the names of Allah are written, that is forbidden because it involves their desecration. If the carving is for a person's name or ordinary writing, then there is no harm.