Is it unable to be pushed by an explosion or does it just get destroyed?

From wiki :-
-It is a common misconception that enough TNT will destroy Obsidian. Even though its explosion resistance rating is finite, additional TNT or other explosives will have no more effect on an individual block than the first.

-Obsidian, unlike most other blocks, cannot be moved by Pistons (normal or sticky).

-Obsidian is one of the three blocks that cannot be broken by Ender Dragons. The other blocks are End Stone and Bedrock.

-It takes 285 times the explosive power of a single block of TNT to destroy a block of obsidian.