Finishing / processing FOOD GRADE prints

I discovered that the ruby nozzle can not be used as the metal base is made from BRASS and normal no zzles for the same reason
the hardened steel nozzles appear to be the only option for FOOD GRADE prints at the moment.
I would like to know what "products" can be used to finish/seal Food Grade prints (example coffee cups) [also reasons why that product]
note must be able to withstand dishwasher.
Thank you in advance

You need to think about your material, not just your finish. Coffee cups and dishwashers will put a lot of heat into the plastic and will soften or melt it. There's a reason coffee cups are ceramic usually. I don't think any of the common 3d printing plastics are suitable for use as coffee cups.