Everyone's a nerd about something. What are you a nerd about?
I know it's an unpopular opinion given current circumstances, but I've always been a huge nerd about Russia. The history, the geography, the music, etc. And as an American, I've always found it fascinating how U.S.-Russian relations have fluctuated over time. We've gone from allies, to enemies, to frenemies. This doesn't mean I support Z or Putin, of course. What are you a nerd about?
I'm definitely the stereotypical nerd in a lot of ways. I'm hugely into Star Trek, D&D (and TTRPGs in general), Pokemon, and sci-fi/fantasy novels, especially Brandon Sanderson and Becky Chambers. I'm running a Pokemon TTRPG campaign.
I'm probably equally nerdy about alcohol though, which is fun, and can augment all the other hobbies. I like to make specialty cocktails for premiers, and events in general, as well as thematic drinks for TTRPG sessions. We don't have a dining room at my house, we have a bar.
I don't actually run any games in D&D myself, I'm afraid, so I can't make much use of homebrew, but I always enjoy hearing what other people are enjoying in their own games!