You're getting hyped before a concert and say you're going all-in.

In practice it means "to the max / fully / like crazy," used to intensify an action or state. It can mean going very fast, being very motivated, loving something a lot, or doing something with full intensity. It's super common among younger speakers and in casual talk, and it sounds more natural than "à fond" in some contexts. It's basically a clipped/slangy pronunciation/spelling of "à fond."

"À donf" does not mean gently, occasionally, by accident. It specifically means "Fully".

On the morning of a big event, you're bouncing between printing tickets, answering calls, and packing supplies.

Literally it describes a headless chicken still moving around in a chaotic way.
In practice it means someone is frantically busy, rushing from task to task, often without a clear plan. It's usually critical but can be said with humor, like "you're stressed and chaotic right now." People use it for work deadlines, travel days, or any situation where everything feels out of control.

"Running around like a chicken with its head cut off" does not mean working patiently on one task until it is finished, staying calm and waiting for instructions, spending time daydreaming and losing track of time. It specifically means "Acting in a frantic/panicked manner, usually trying to do many things at once".