If color is not an issue, mineral oil works, and is non toxic (it used to be given to kids for constipation, though that’s not done any more because if they breath in the liquid it’s bad for the lungs, not because the dries stuff is bad).
As mentioned, shellac is supposed to be safe once the alcohol evaporates off. It is sometimes used as a wax based coating for fresh fruit. But the official Material Safety Data Sheet for ‘Shellac gum’ makes the following statement: “Hazardous in case of ingestion. Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of inhalation.” That’s actually a new one to me, as I have seen other sources state that shellac is ‘food grade’ and therefore edible. My guess is that the people that are using it in foods are not going to the local hardware store and buying a few cans.
So who knows which product is safe? When in doubt punt.