You don’t need a client for that. Just a a key generator then use that new key to login to any client you like.   As for the relays I don’t see the purpose of a blank relay list but most client have a list of default relays that could be easily deleted.   

https://yeghro.site/vanity-nostr-keys/ 

 When my brother joins nostr and opens to be on a family private relay. I don't want him to start deleting preloaded relays unfollowing 300 npubs he didnt follow.