He-177 nuclear bomber
Also of interest Hogsnortrupert, the He-177 V38 airframe, plus two others which I can't recall, were converted at the Ju-290 factory in Prague with an outsized bomb bay for the planned Nazi A-bomb.
It is a highly disputed claim. By 1945 the He-177 was not fast enough to overfly Britain even at altitude because of RAF air superiority so attention switched to jets.
The first Ju-287 jet engined bomber used the forward and midwing fuselage of an He-177. It also had precisely the same bomb bay dimensions as the V38, which leads me to suspect the Ju-287 V1 was in fact one of those three He-177 converted to the nuclear role at Pargue.
The Ju-287 V1 had a non retractable fixed spatted undercarriage and flew some 17 test flights by about October 1944, when test flying was abruptly abandoned.
According to overheard conversations (bugged) at Camp 11 after the war, General Dornberger recounted to a fellow general how he and Werner von Braun went to Lisbon for talks with two officials from General Electric Corp.
The Nazi A-bomb project and the Ju-287 both appear to have been abandoned about the same time suggesting to me at least that some Nazis were already negotiating with Uncle Sam in 1944 for the abandonement of a nuclear attack on the west.
In October 1944, the Manhatten project removed Germany off the Strategic bombing Survey's list of nuclear targets for the US A-bomb.