Pretty sure the Reich never had a serious nuclear program, though. Apart from Nazi ideological rigidity retarding their contributions to science (e.g., snubbing atomic physics as "Jewish science"), I also heard they had maybe 60 scientists working on their nuclear program as something of a "side-show" that they never took seriously.
Now, ATL where a far less idiotic regime remained in power (such as Imperial Germany in a Central Powers victory), I can easily imagine Germany's long-running proficiency in science and innovation trundling along uninterrupted, without ideological know-nothings poisoning scientific research with their schizo bug-bears. Might also help not to drive away Jewish scientists (read: Albert Einstein) who pioneered atomic physics and their uses in the first place, which may require easing up all the anti-Semitism the OTL Nazis capitalized on.
Assuming that all happens, a victorious Imperial Germany getting the bomb first is a real possibility — though judging by how others got their hands on nuclear tech IOTL (despite the US's best efforts at preventing that), it won't be long before Germany's rivals reverse-engineer it and build bombs of their own.