The thing about the Anakin idea is it inevitably begs the question… why then? Why wouldn’t Anakin have appeared to him earlier? The Han scene is some combination of a Leia-induced hallucination and a visual metaphor for an emotional breakthrough, but Anakin’s ghost would just literally be the sand man himself manifesting. Why then and there? It’d also remove some of Ben’s agency from his turn, making it less of a personal choice and more of a response to getting a bit of a scolding from Grandad.
Of course, the Force Ghost question already exists in the movies as they are, and even in the OT, Obi-Wan’s choices of when to appear or not seem entirely motivated by plot convenience, so it’s not the end of the world. It’s apparent why Lucas decided when writing the PT that no one learned how to become a ghost until afterwards, haha, to avoid this sort of thing.
I know the wider canon does not matter but I believe there’s some place where it’s established Force ghosts could only talk to willing light-side users.
As someone who has collected and read literally every single canon story, I’m 90% this has never been established. Sadly there isn’t much Force spirit lore 😕