EDIT: On the topic of Boba, his survival is plausible. Death by Sarlaac is a slow, slow death by digestion. Boba could have escaped before the digestible fluids cut through his beskar armour. Beskar being one of the most durable metals in the galaxy. And his death was kinda lame. I totally support his survival.
Boba is dead, and i love Boba, but it was lame as hell that they just wouldnt let him stay dead.