Personally I'm not the greatest fan of challenges that have too many rules and regulations so I only have one: read as much (or as little) Russian literature in 2020 as you want to and share your thoughts if you so desire! I have a recommended reading list that I'll add the link to at the end of this post for ideas but how you define Russian literature is up to you.Here are some titles, in no particular order, that are on my list of things to read, but I'm not committing to anything specific at this time.
The White Guard or Heart of a Dog, by Mikhail Bulgakov
Shorter works of Tolstoy
Last Witnesses and The Unwomanly Face of War, by Svetlana Alexievich
Oblomov, by Ivan Goncharov
Most anything by Teffi
The Idiot and The Possessed, by Dostoyevsky, also short stories
First Love and stories, and Sketches From a Hunter's Album by Ivan Turgenev
And Quiet Flows the Don, by Mikhail Sholokov
The works of Vasily Grossman
Jacob's Ladder, by Ludmila Ulitskaya
A couple short things by Sholzhenitsyn I've got lying around
Red Calvary, by Isaac Babel
Stories by Ludmilla Petrushevskaya
So, you know, hardly anything.