The map at www.opensnowmap.org is not enough ?
On this page you can find ski extracts from the openstreetmap database in various formats.
This extract contains, recursively, way, nodes and relations tagged with:
Mobile - Vector Format
Ski pistes are now integrated directly in Osmand map files, you just have to enable the winter+ski style and no longer need to download ski maps separately.
Mobile - Tile Format
Overlay (transparent) tile packages up to zoom 16 are regularly extracted. They are offered in MBTiles sqlite format, please contact your mobile application help channel for support in converting them.