He continued: “And they only appeared there, and they were the most awkward-looking creatures, and we decided, ‘That’s gotta be in our show.’ So we have an Ugnaught riding a blurrg — you will see that on The Mandalorian.”
What about the Blurrg-riding dude, Kuiil, featured in the trailer? What about his species? The Star Wars website has a bit to say about them, calling Ugnaughts “a species of diminutive humanoids who divided themselves into a tribal hierarchy.”
“They have pink skin, white hair, upturned noses, and thick layers of jowls. [Ugnaughts] found work across the galaxy everywhere from the Jedi Temple and Coruscant to Cloud City and Lothal,” so they’re an enterprising group of weirdos. They were first featured in The Empire Strikes Back and sadly, the majority of Ugnaughts across the galaxy were enslaved all over the galaxy. Three large groups of Ugnaughts earned their freedom by building Cloud City.
Source : https://www.distractify.com/p/who-is-kuiil-the-mandalorian