This advice was given to me 27 years ago at a time when I had to go to a corporate function with my husband.
It served me well as I still do an abbreviated version after all these years.
As far as interaction with people, hugging and kissing - yes, definitely wear a mask but also tell a fib, that you have a cold and prefer to protect people from catching it. That will both give you an excuse to avoid close physical contact but it will also diffuse people asking 1,000 questions about the transplant. Let them focus on the bride, not on you. Wash your hands multiple times through the event. For food, only eat what feels hot to your tongue. No salads, fruit or uncooked foods. No shrimp cocktail lol. For drinks, do not use glasses. Either bottled water or drinks in a can - drink from the bottle or from the can, do not pour in a glass. Get your drinks unopened, YOU open it. Otherwise, just enjoy the event and seeing family and friends with an appreciation for the fact that you got a life extension and will be able to enjoy many more weddings in the years to come.