Of course, we're all conditioned to be ashamed of bodily functions in public and unused to the idea that as we were when we were children, we might become without control and wholly dependent on others.
But we're also adults, and can understand that when someone we love is dying, and losing their facilities, that they don't have to be ashamed or fearful of those matters, which are trivial in comparison to the slow death which they are experiencing.
Hand holding is easy, except when even that causes discomfort, but it leaves larger matters which hold the mind unsettled and unaddressed.
I don't have an issue with bodily functions, I just don't see why others should have to deal with mine. Shakespeare's 'seventh age of man' is one I hope to skip.
I'm still not quite sure what feature of death particularly concerns you? I have been with dying people at all phases. Is it what Catholics would call the "in extremis" phase? A period of psychological suffering, realisation with or without pain?
You seem to be searching for some flash of sensibility to the fact of imminent finality. If so, yes, I have witnessed that, but only once. There was some fear but more surprise: "By God, I'm going" (from an agnostic).
More often people I have been with have gone very peacefully, without theological debate of any sort.
This from my very elderly mother: "no more tea dear, I think I'm going on a little journey".
When offered a recuperating trip to the south coast of England, while on his death bed, King George the fifth said "ah heck Bognor", then he died. An excellent decision, if you know Bognor Regis.
I detect no final angst in that declaration. But he was the head of the Church of England and renown for his lack of imagination.
As for hand- holding, when the dialogue is done and the breathing is getting rattly, I'm still convinced it remains the simplest way to show love and support.