Would make more sense to get his “non-yami” version in DSOD. He was more prominent in the movie, plus I don’t see them going back and making a new LD for DM. It’s been well over a year since we got a character for that world.
According to event archives, they first become unlockable in May of 2019 in the Tag Duel tournament. I remember that, because right after, players were abusing their pre-nerfed skill Masked Tribute in Subterror decks back then.
It seems we will get Ryou Bakura soon after all. In this events dialogue between Joey and Teà, she claims Tristan and Bakura will be coming to DL soon.
I got my hopes up for Ryou Bakura because of that dialogue ... but is that our only hint ? No dev mentions the line of duelists they plan to release and when ? XD
Though probably knowing and waiting would take away from the joy of the surprise