The German public cares, US nukes are kind of an accepted, and mostky ignored reality. French nukes would wake up the public. The big party that cares about US nukes on non-US planes, e.g. Eurofighter, is the Pentagon. As they have to certify the aircraft, they are a lot less eager to do that fast or at all. Because the Pentagon prefers NATO nations, or any other allied nation, to buy the F-35 over other models.

And the French, which excluded their nukes from NATO oversight, might actually be reluctant to share them with Germany. Using Rafales insteads of Eurofoghters might helo, but then Germany is in the same position it is with the F-35. With the added "benefit" of a potentially hurtful public debate.