According to begun appearing around the market area so you can test them out yourself. YouTuber Mokeysniper has gone all out with those tests, making a video that demonstrates every legend in the game launching off the pads and also shows off the other possible interactions.
While Lifeline's ultimate can't be summoned on top of a launch pad, they can be used to bounce grenades, traps, and other projectiles around, which skilled players will doubtless find some use for. Also, here's your confirmation that hitting the jump button on a pad gives a boost to your leap height.
