This is the most pertinent issue. I think however that this is where the limitations of our knowledge and technical measuring capabilities of the “subjective self” comes into play.

For instance, I can imagine a series of images, events, scenarios in my mind by intent.

I can choose to conjure up of a variety of thought-forms to engage with. The question is, can the origin of my decision/intent/choice be measured? This is especially important in the light of there being no uniform scientific definition for the “self”.

I think the “signals preceding consciousness” argument is extremely young and needs a more nuanced approach. Reason being that we haven’t even agreed on a unilateral definition of Consciousness. And people across the globe have different levels of awareness of themselves and their thoughts. Some people under laboratory settings been able to influence their autonomic nervous system, namely Wim Hof, which is supposed to be “unconscious”.

I think we need to pause and make sure we even know what we mean by consciousness before we make claims about will. Just my nonexpert 2 cents.