As we all know for those who read the last two Magic War chapters, the Cybermen appeared. However, there are not the Cybermen you all,know from Doctor Who but rather created in their image .
Basically before the war, several Cybermites were made by a unknown company.
After ,magic was exposed however..the government shut down LexCorp and sent a TYGER agent to nuke New York during the Avengers (2012), killing off the avengers. With Lex arrested and Stark dead, TYGER took the technology and combined them to mass produce the Cybermen.
Now as this is a AU, it’s vital to note that every marvel film after the Avengers never happened so Bucky will not appear.