I think some time ago someone asked for duelist here on the fediverse? That said, I found this awesome #yugioh online client fully compatible with #ydk decks (the same format #ygopro uses) so you can import your cards very easily and enjoy playing with humans and bots alike.
If you wanna play some time my handle is Daisuke 😁
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko