The thing is for this discussion, analysis of the ego and the role of "the mind" or however you want to call it, I simply don't think it matters for the question of free will. It's one of causality at the beginning of the universe for me. The mechanism through which humans would drive their thought process or behavior is besides the point if the cause is the initial state of the universe and how all the particles and forces interact from that point onwards. A rock on the ground's "life" (path through universe) would be as predetermined as ours, it wouldn't change it if the rock had thoughts or an ego.
The discussion about the ego and "the mind" and the "who you are" in that sense are then still useful for the human to feel comfortable in feeling like they have agency, and I am aware of Buddhist philosophy in finding peace through detaching from our inner voice and gaining wisdom from not letting ourselves being driven purely by what we think we are or "what the ego says we are", but I think it's besides the point in this context (but very useful to include in a balanced "diet of thoughts").
Maybe the ego is an evolutionary defence against nihilistic traits so we all don't kill ourselves by realising none of what we do is any agency and it's all predetermined by the start of the universe. But anyway this part of the discussion enters into a rabbithole detached from the core discussion of there being free will or not, at least to me, because I cannot accept that a core property of the system "universe" and the definition of it's causality or not could depend on the thought process that goes through minds of humans in some remote part of that very universe. A detail about the higher level thought process of some "blobs of particles" in the universe don't define the way the universe itself works. Our relationship to the self doesn't have anything to do with physical reality of if-this-then-that. In other words the causality doesn't care what we think of it, it's either all pre-determined or not, our opinion doesn't matter.
https://www.gocomics.com/calvinandhobbes/1988/06/07