Yeah, that’s probably what a lot will take it as, that Anne is offended Hop Pop assumes she’s hetero.
Personally, I don’t think that makes sense. If they really wanted to make Anne lesbian, they would’ve just done it.
In kids shows, homophobia doesn’t exist, so no one would be “assuming” heterosexuality or homosexuality, let alone getting mad at it. People just exist and do whatever, and no one questions it. Owl House pretty much does this.
If Anne’s sexuality was really ambiguous, Hop Pop would’ve said something like “so, you’ve been dating at home”, to keep it more neutral. The deliberate mention of boys implies Anne is into boys