Interesting thought exercise, let me try something:

Only if we can predict everything ourselves do we not have a choice. But since we don't know what we don't know and that may occur at any moment (black swan), we can only act given probabilities.

Then what we control is our level of appetite for risk of an undesired outcome.

That risk is not data that we can reliably measure and assert. So it creates randomness/stochasticity in the system.

That's why I was speaking of open vs closed system.

Randomness provides agency.

That randomness is subjective. You may well still be predictable for an omniscient person. But that person would not have any agency. You do as long as your choice does not rely upon knowledge.

I guess that's why the human society is weird in a sense. People act from belief they have no certitude about.

A clock does not do that, there is no metacognitive process to influence an action toward a yet unrealised future. Seems incomparable?

But yes, other than that, there is not real accurate way to deny compatibilism I'm afraid.

In fact, true agency is the attempt to eliminate choice.

It is like being in a Labyrinth where the walls are moving.

The clock sits in the labyrinth and gets crushed by a moving wall.

An agentic person detects the movements and recalibrates.