I know there are a lot of subgenres for nsfw game dev discords like bara, yaoi, furry, etc..., but a purely nsfw game dev discord server..., hu now that I think about I can't recall a general all around nsfw discord server, so I'm not sure, :o
Could always try the NSFW Nexus discord server, they're about as generic as you can get when it comes to NSFW discord servers from what I've seen: https://disboard.org/server/877831841418186802