Exactly! the USN doesn’t really need a high-end German Type-212 or Japanese Soryu. A Type-209 vanilla diesel-electric will do!
I’d spring for AIP option. I understand it’s now available for the 209.
Say a half dozen or so for the Gulf of Mexico/Caribbean, a half dozen or so working out of Southern California, and maybe a half dozen or so working out of Guam. That would probably be less than the cost of a couple of the nuclear powered boats.
If the navy said they didn’t want them, give them to the Coast Guard.