I think Kenku, Tabaxi, Tortle etc would be difficult to add unless they changed some existing NPCs to those races too. Shopkeepers etc. Populate the world with them.
Would love to see Kobolds as a playable race ? let me bring Deekin to Baldur's, pls, especially since they exist in the game already. Genasi could be a shout, too. Maybe even Myconids since they're in the game too – they aren't really individuals, but then neither are mindflayers and there are individualistic mindflayers in-game.
Perhaps a full Orc? More monstrous races. Goblins, Orcs, Bugbears, along with the Kobolds.
As for classes, it'd be more about adding subclasses to me. More sorcerer origins, swashbuckler rogue, etc.
Not a race/class, but I'd like to see more mental half-feats. Seems like many of them are CON or DEX, very little in the way of INT or WIS +1 with another bonus.