Roger Penrose is pretty much the only dude looking into consciousness from the perspective of a physicist
He thinks consciousness has to do with "quantum bubble collapse" happening inside our brains at a very very tiny level.
That's the only way free will could exist.
If consciousness is anything else, then everything is predetermined.
Like, imagine dropping a million bouncy balls off the hoover dam. You'll never get the same results twice.
However, that's because you'll never get the same conditions twice.
If the conditions are exactly the same down to an atomic level... You'll get the same results every time
What would give humans free will would be the inherent randomness if the whole "quantum bubble collapse" was a fundamental part of consciousness.
That still wouldn't guarantee free will, but it would make it possible.
There's also the whole thing where what we think of as our consciousness isn't actually running the show. It's just a narrator that's summarizing everything up immediately after it happened. What's actually calling the shot is other parts of our brains, neurons in our gut, and what controls our hormones.
We don't know if that's not true either. But if it was, each person as a thing would have free will, it's just what we think of as that person does not have free will.
Sounds batshit crazy and impossible, until you read up on the studies on people who had their brains split in half at different stages of mental development.
There's a scary amount of shit we don't know about "us". And an even scarier amount we don't know about how much variation there is with all that