Here’s my hc on how they could have all survived…
K2 somehow overpowers the stormtroopers and gets away, but still locks Jyn and Cassian in the vault.
Bodhi manages to knock the grenade out of the ship like the badass that he is.
Baze lays down cover fire for Chirrut as he walks to pull the lever, and they fight their way back to the ship where Bodhi is waiting (picking up any stray rebels on the way).
Bodhi takes off and flies towards the citadel tower, determined to find Jyn and Cassian. Everyone is shouting at him to just leave them, because the Death Star has fired and the destruction is coming their way. Bodhi refuses, and circles the tower until Chirrut suddenly yells “They’re down there!” and sure enough everyone looks towards the beach and there they are, followed by K2.
They get them aboard the ship just in time, and Bodhi books it out of there. There’s confusion about where they should go, but eventually it’s decided they need to disappear, because the Empire wants them dead and they essentially went rogue from the Rebel Alliance.
Their ship enters hyperspace, then it can cut to Vader’s scene cutting a swath through the rebels.