Is Datasmith for UE5 already available?
What do you mean by that?
In Unreal Engine 5 Early Access, that was released last week, you should have access to datasmith.
For this version, you should expect same functionalities than in 4.26, modulo instabilities due to the merge and current EA focus that is not really enterprise.
Make sure you have the plugin enabled. Then you can access it through a dataprep asset or else it is no more an icon in the toolbar but in the Content submenu.