Maybe should focus on someone like Stephen King or Brandon Sanderson who actually pump out writing.
Honestly, the amount of writing doesn't even seem that useful of a metric. Stephen king only wrote ~3x more than George, and about 6x more than someone like Nabakov (1.5 to 2 million words across two languages). The real takeaway IMO is to just write regardless of the technology you use
And while not a novelist, Tarantino famously writes his screenplays all by hand as well.
Some notable examples I remember include J. R. R. Tolkien, Patrick O'Brian (who wrote all 21 books in the Aubrey-Maturin series by hand, and claimed at one point to write with "ink and quill"), Nabokov, Joyce Carol Oates, Ursula LeGuin, and Truman Capote.