At a root level, all modern submarines will nowadays start to look the same from the exterior.
They will have smoothly blended trapezoidal sails, multi-blade screw propellers, diving aileron-like devices (sometimes foldable) and a tapered nose with torpedo-tube openings. The goals of all designs from all countries are the same, quietness while moving in depth underwater. In that sense - designs will be more or less similar.
Just like all recent mid-size airliners (like B787 and A350) have two wings, two engines and three tails. If you get to the inside details, things are radically different.
I don't agree that the Chinese are incapable of developing fuel cell technology for submarine propulsion. I am guessing you have never been to China - which figures. They have moved on from simply copying Western designs (in anything).
You are welcome to your opinions, but if you are not a submarine or naval craft designer (which I doubt you are) then the less criticism offered, the better it is.
I don't think he knows.