So, I'm sure it would be easy to ping your phone when a Sentry mode event occurs. However, playing Sentry mode clips remotely would take much more work, which would be the gradual next step. Even if they restrict Sentry mode recordings to Tesla-provided storage drives, getting those videos over the air to play smoothly on your cell phone is harder.
Imagine being pinged every minute or two for hours because people were outside looking at your Cybertruck while you were inside a work building or on the other side of the country while you parked at an airport. The truck's and your phone's battery life would take a hit.