When my progeny were in lower school at an old, elite, well known in some circles, private day school, NOT affiliated with any religion/church, The Lion, The Wit, and The Wardrobe was required reading in the third or fourth grade and the students were encouraged to read the rest of the Narnia books for pleasure.
That was quite a bit ago, I don't know IF that school still has it as REQUIRED reading, but most of the kids DID go on and read the other books.
The elites reading lists included Lewis’s Lion Witch and Wardrobe because elite education was built on Christian based civic religion.
Not seeing that anymore. Christian and civic homeschoolers and the vanishing small numbers of Christian schools and perhaps a protected elite or two are reading and discussing the books that our children had 20 and 30 years ago.