I have a scar on the top of my foot from bunion surgery (two years ago) that is still tender. What can I do to move along the healing?

Nothing. At 2 years, healing is complete. Scar maturation usually occurs in half that time. At this point, you need to treat the scar tissue which is likely causing your pain. See your surgeon who can recommend treatments such as steroid injection, ultrasound therapy and if necessary, surgical scar revision or excision.
Massage & silicone. Topical scar massage and silicone gel sheeting may provide some relief until scar maturation naturally improves sensitivity. If this does not resolve discuss with your foot surgeon to evaluate for possible scar neuroma.
Depends. If the scar is thick than cortisone injection or topical steroid can be applied. If a nerve is caught in the scar than physical therapy or surgery maybe necessary.
Sometimes not much. You have probably tried a variety of scar creams and massage. If the discomfort has persisted, sometimes, depending on conditions, a cortisone injection can be used. Many times, the best solution is surgical excision of the scar. See your foot surgeon. Dr l.
Avoid pressure. Go back and revisit your surgeon, you may have a keloid formation, or thick sensitive scar, mean while avoid pressure , and apply and rub over the scar with vit- e ointment to desensitize the scar area.