Is it possible to round the edges of a curved surface i.e the ends of a cylinder
Yes. You can do it with Follow Me or there’s at least one extension that will do it. If the cylinder is a small diameter, you’ll probably have to scale it up before rounding the end.
And if you want a flat top and some thickness…
Just as a “many ways to do the same thing” thing: Instead of insetting the whole shape, you could have just selected the three lines (top, curve and side) and then used the off-set tool: it would have saved moving the un-necessary lines.
(I would double click in the shape, then draw a selection around the origin with [shift] to de-select the face and other lines)
And the notch thing Gully suggested could be drawn on-top with a curve/wedge/pie; adding to the shape rather than cutting into the shape.
You’ll often find in my gifs a little something extra. I chose to do it that way to highlight that particular move tool function.
Thanks to Gully_Foyle and the rest of you for your input.