Got to chuck one in.. I'm not getting this flickering that's being discussed here? Or maybe I am?
I do have a couple of bugbears.. the normals are not perfectly matched, even after welding, because of uneven mesh density, I think. Also, the geometry matches only if there are an even number of segments around the minor circumference, and cap rings. You could put in some math to constrain to that.. but that would just be more nodes.
This shows the GN followed up with a Weld and Subdiv
(Blender 3.0b) Crits welcome.