I found an old thread that was basically this exact same question, but it came before 9th and the new Imperial Armour book so I don't think it is still relevant.
My question relates to the Imperial Guard Cyclops Demolition Vehicle. It's demolition charge is represented by a heavy-type weapon. It then has the following abilitiy:
Demolition Vehicle: When this unit is selected to shoot with its Cyclops demolition charge, you must target and resolve attacks against every visible unit within range (friendly and enemy). After this unit shoots with its Cyclops demolition charge, it is destroyed.
The old version used to say 'at the start of your shooting phase' but they changed it. Can the new version pay to fire overwatch, select its bomb to shoot with and then explode? If so, I assume that the charge automatically fails since there is nothing left to charge?
Also, the new overwatch wording says 'when a model fires Overwatch, it does so at the charging unit'. How does this interact with the Demolition Vehicle wording that says 'you must target and resolve attacks against every visible unit within range'?