Who did Matt Smith play in Rise of Skywalker?

It was announced in Variety in August 2018 that he was attached to the film but this exclusive was accredited to "[unnamed] sources"*. From that point onward, there were no official confirmations that he was going to be in it aside from a quickly deleted tweet from Disney, and Smith actively denied it in multiple interviews.

Emily Zemler One takeaway: Matt Smith is not in the next #StarWars movie, despite reports to the contrary. He told me, "As far as I can tell, I’m definitely not." (Although maybe we'll be surprised by his secret keeping in December.)

_{^{Via Twitter - Mar 7, 2019}}

There's no indication that he was ever attached to the film and his total absence from the final cut would seem to be proof-positive that the Variety "exclusive" was just speculation.