The new hotness is the Constellation-class frigate which chose a mature design to keep costs down. That was until feature creep completely consumed it in record time:

"At one point the Constellation design shared about 85 percent commonality with the original FREMM design, but the alterations have brought that commonality down to under 15 percent, a person familiar with the changes told USNI News."

https://news.usni.org/2024/04/02/constellation-frigate-deliv...

Depends on what you mean by “working.” DDG-1000 is still kicking around trying to figure out what to do with itself. DDG(X) is in a requirements development phase. FFG-62 is actually getting built. There are various autonomous surface and sub efforts that may turn into something.