French seem less anti-nuke than Americans. The issue with nuke submarines is cost, I think. US wants big, long distance deepwater subs. Most buyers seem to want smaller, stealthier, (and cheaper) subs for more defensive use.
Just casual observations by me. There are FReepers who really know this stuff.
The USN buys subs for global power projection. Which require nuke power.
Subs designed for coastal, local or at most regional ops doen’t really benefit from a nuke plant. Particularly with modern technogy like air independent propulsion and the like that allow conventional subs to stay submerged much longer.