The first big patented invention here is usually credited to Sherman Poppen who filed in 1966 for his Surf-type snow ski. You were supposed to cling to a rope. He began manufacture of his Snurfer. Below is its illustration page.
Jake Burton Carpenter, who broke a finger while using a Snurfer, is credited with improvements to the snowboard concept -- he made it wider, provided high back bindings, and a steel edge to help turning. His first patent, filed in 1990, is for a Snowboard binding system, as illustrated below.
What about the Seated skiing or snowboarding device, illustrated below.
Or the Wrist guard for snowboarding, illustrated below.
Training aid for snowboard maneuvering, which features a miniature snowboard, as shown below. Let your fingers do the walking...
list of snowboarding patents since 2005 published through the PCT "World patent" system.