In your dream, the snake is a difficult problem in your life and something that makes you unhappy. In fact, it's a symbol of your dismissal.
The snake in the lunch box is a symbol that you want to digest the unhappiness of being fired, or subconsciously encourages you to let yourself digest this unpleasant thing.
Buying a snake to eat, suggesting or encouraging yourself to be fired is not something you thought unacceptable or impossible. Even if you have a second time, you can beat it.
The snakehead you bought is very big and thin, which symbolizes firing your boss, and you should have the confidence to develop your own career.
It's a pity that you woke up without the hint of completing your dream, which shows that you haven't finished the process of building your confidence.
This dream has no other bad meaning, but it is a pity that the process of building confidence has not been completed. But you can gradually build up your confidence.