I've never tried petg in the dishwasher, I'd guess I'd probably deform something thin, but I don't know. Putting it in the dishwasher won't be enough to clean it though, you'd need to boil it for a while. A dishwasher won't get hot enough to kill the bacteria growing in the recesses.

Most 3d printed materials, including petg, won't have a glass point high enough to boil them.You'd need to keep it in boiling water long enough to raise the temperature of the innermost recesses. Basically, there isn't any good resource for food safe 3d printing because it's just not worth the effort.

If you do want to do it, you'd need to make sure: you have food safe filament that can withstand boiling temperature without softening, your printer can get hot enough to print that filament, your print head/nozzle is made out of food safe components, and you boil it for a while after every use.

Resin coating can lower the temperature requirements because of being able to clean it normally. But you still need to make sure you have food safe filament and print head.