In the last few bars of Liszt's masterpiece, Liszt actually wrote a crescendo which can't possibly be played on the piano. I don't know how to interpret it. How do you approach it? Is that more of a gesture thing (like putting more weight on the keys after having played the notes)?
It's often not a bad idea to check whether or not IMSLP has an autograph for a piece in the public domain, or failing that, to check other editions. In this case, IMSLP has a holograph manuscript which shows the point of the crescendo distinctly to the left of the second chord. I would play the second chord somewhat louder than the first, and break right back to ppp for the third chord. The holograph is here.
In many places in Chopin's music, he wrote hairpins like the one on this score to indicate rubato rather than a crescendo or decrescendo. If you used that concept here, it would mean taking a bit more time coming into the ppp.