Plus one for making sodas & water kefir. I had to stop drinking alcohol for a bit last year due to a stomach issue and homemade soda & water kefir were great, especially for taking to parties. Water kefir expresses hops beautifully so that's a nice beverage to make if you crave something hoppy. Lacto-fermented and ginger bug-fermented sodas are really lovely, too. Water kefir, lacto and ginger bug-fermented sodas can all be encouraged to go sour and are a nice non-alcoholic substitute for sour beers.
I haven't done it yet but I'm intrigued by brewing non-alcoholic beers. You can brew a regular batch and then convert part of it to a non-alcoholic brew. So you could potentially drink the same beer you're serving to your buddies without the alcohol. I really need to try this - there are definitely times I crave the aroma & flavor of a beer but don't want the alcohol.
It sucks to have to give up something you enjoy but maybe you can turn this into an opportunity to explore some other fun ferments.
Mary