Mental processes, physical quantification

On the question of freedom of choice:
It is clear that physical processes occur in the background (not related to the person himself - occurring in an ‘unconscious’ manner), but there is a factor that is unknown and cannot be measured, the mind itself.
And from the way it looks, it is itself problematic for physical understanding.

How can one decide this question when the factors are not clear?
Another question, were the Libet experiments able to isolate the ‘point of choice’? If they relied on some kind of ‘spark’ that materializes some time before the overt choice, how can one know that this is not a kind of ‘suggestion’ that the brain offers to the mind? (Then the person chooses whether to accept it, or not)

The same goes for other things related to the body-mind.

This is a general question and there is no point in giving a general overview. If you have a specific question, raise it. Several options have been raised to test this empirically, and they have been discussed extensively in the books of the liberal sciences.
There you can also see your proposal to interpret the results of the Libet experiments, which is called in the literature “Veto”.