Stipple Texture
I am using Affinity Designer (not Illustrator), so I have found ways to create similar effects, but they are not quite the same. Affinity Designer does not have Graphic Pen or Grain. The closest thing is Noise, which can be used with any colour or gradient. The only option is what percentage of noise. Generally the stippling is more subtle.
I did another project with stipple texture in Hayden Aube's class: https://www.skillshare.com/classes/design/Vector-Illustration-Playing-with-Texture/998065955/projects/85819?via=class-details-projects-page