Mainly a question to sate my own curiosity and potentially have the Nazis waste more resources on an essentially useless super weapon, but couldn’t they have created nuclear artillery? Make the bomb, stick it in a modified Gustav gun, and fire it somewhere in range. It’s no B-29, but as far as I’m aware it should theoretically work as a delivery platform.
The easy answer is no.
Slightly more detailed is that the early nuclear weapons where far too heavy (roughly 10,000 pounds) for anything except the 80 cm Schwere Gustav "Dora"railroad gun. That weapon too five weeks to prepare to fire once reaching its destination and required a crew of 4,000. Bound to draw some attention., especially from a thousand or so B-17/24/25/29/32 and or Lancaster/Mosquitoes along with at least that many P-38/47/51 and/or Spitfires/Tempest/Typhoons. It also had a max range of 47 kilometers (29 miles).
The other factor is WHY early bombs were so damned heavy, wiring. While less an issue with Little Boy, where most of the weight was high explosive, Fat Man, and all early implosion weapons, were loaded with heavy copper wiring, capacitors and TUBES (no transistors existed at the time) Every bit of the eletronics had to work perfectly down to the millisecond (the effort taken to ensure that every length of wire discharged at the same millisecond itself was incredible) and tubes of the day simply would not have survived the firing sequence (I have profound doubts about the Little Boy design maintaining the breathtakingly precise alignment necessary to induce the fission reaction after being fired out of an artillery piece)