I did find a book of piano music compiled and arranged by Alan Jemison as part of his St. John Bosco Hymn Collection (Volume 1 - Advent Hymns), so at least my piano-playing daughter can fill our home with nice music for the season. My set has a spiral binding so it sits open on the piano and it came with sung recordings of all the music, which is helpful for those pieces I've never heard before. It's a great selection! He also offers lots of other piano and violin music of traditional Catholic hymns for beginning musicians.
You have a few more weeks until Advent begins, but since his site is kind of low-tech and all orders must be mailed in, I thought I'd post this early.