Who is eligible to play sitting volleyball in Canada?

It depends on the level.

• Recreational and domestic play: anyone can play, including athletes without an impairment. Individual competitions set their own eligibility rules, and many Canadian recreational leagues encourage mixed rosters.
• International play and national teams: athletes need a permanent physical impairment, which may be progressive or non-progressive, and must meet the minimum impairment requirements for the sport. Athletes must be classified before competing and are placed in VS1 or VS2.
• Impairments Volleyball Canada lists as eligible include limb deficiency (amputation or limb dysmelia), leg length difference, hypertonia, ataxia, athetosis, spinal cord injuries, loss of range of motion and loss of muscle strength, among others.

Source: Volleyball Canada sitting volleyball page and sitting volleyball info sheet (volleyball.ca).