If anyone is wondering where the association between alligators and Erika came from, a typo in the preview for the first chapter of GIRLS und PANZER - phase.ERIKA (https://mangadex.org/title/20014/girls-und-panzer-phase-erika) changed her saying "I'm finally here!" to "I'm finally alligator!" which the Japanese community memed on like crazy.
In chapter four, Erika was drawn with a plush alligator strap on her bag making it officially canon.