“bear in mind that with newly upgraded B61 that the yields can be dialed way down. Would there even be a mission for this?”
There is a penetrator version.
https://www.globalsecurity.org/wmd/systems/b61-11.htm
And it’s not to be trifled with.
There’s a -12 version now and it makes it even more capable.
https://nationalinterest.org/blog/the-buzz/the-f-35-the-ultimate-nuclear-bomber-25932