Starting from November 22, 2019, Pokémon Hong Kong and McDonald's are giving out a double sided poster with a puzzle and a TCG playmat with exclusive artwork. While supplies last (it's limited quantity).
It looks illustrated by Kouki Saitou, that also has illlustrated the current Stars Collection set for Hong Kong and Taiwan. This could be the artwork for their new unannounced set.
It's unknown what material it's made of, I am assuming from either cardboard or thick paper. While supplies last.
In the puzzle you need to spot the 8 new Pokémon. The answer is in the article if you are interested.
Update: Kouki Saitou has confirmed to us it's been illustrated by him. Since there is a Shiny Altaria and Reshiram on the artwork, the chance of it being artwork for the next upcoming set, is very high now.