Well... I'm not sure if this qualifies as dissociation / derealization.

I've never spoken of it to my pdoc or to therapists I've seen in the past.

But I have quite frequent episodes where I become, how shall I say, hyper-aware of my body, particularly my head, arms & hands. Often it occurs at meal times & I become especially focused on my hands & arms as I eat sort-of like they grow in importance in terms of my perception of myself.
I get a feeling like my consciousness is sort-of floating inside my body & is kind-of consolidating up in the area of my head, arms & hands. It sounds really bizarre when I try to put it into words, I know.

It's an experience I've had for many years in one way or another. The way I experience it, & the circumstances, have changed somewhat over time. But these changes have, I think been just variations on a theme. It seems like it's become more frequent over the past year or so.