However both Scavenger's Reign and Pantheon feel distinctly different from Japanese anime. They have a much more Western aesthetic eye visually, narratively, and especially in terms of music I feel.
Having just watched Scavenger's Reign, it differs from both Lem novels in an important way.
Lem uses characters as an excuse to tell something about the portrayed worlds. Scavenger's Reign uses the world as a backdrop to tell the story of the characters.
(Same goes for Solaris, although Tarkovsky's adaptation reverses that.)
Scavengers Reign: https://www.youtube.com/watch?v=NWQH8cMpWTU
Pantheon: https://www.youtube.com/watch?v=z_HJ3TSlo5c