I would rack the finished beer onto the guava. For quick and minimal sanitation of the fruit, prep it for the beer and then freeze it for a couple of days - the alcohol content and low pH of the finished beer will inhibit an infection. I’ve done this a few times with peaches and never had a problem, but bf you’re going to worry about this not being enough and it’ll ruin your brewing experience, then you can soak the fruit in vodka first. Also, guava has pectin in it, so you may want to add some pectinase to the prepped fruit, but since you’re making a wheat beer some extra cloudiness might not be an issue.
