It’s not particularly aimed at kids, but it’s more for high schoolers/young adults. I’m just gonna list the stuff that’s in it so you’re aware:
SA, Abuse, exploitation, sex jokes, bdsm, sexualised characters (specifically adults, no kids being sexualised), mildly graphic scenes, swearing, drug and alcohol use, trauma, gore, violence, crude humour, lgbtqia+ representation (I’m only listing this because of some others religion), depression, and weapon use.
NOW, I watch Helluva Boss and tbh, it’s not the BEST show for 10 year olds, but let her watch it. Don’t let it go and let her pick up on swears or violent stuff, but let her watch what she wants to watch. If she does pick up on the behaviour and is showing signs of growing up too quick, let her know but don’t make her feel targeted. That’s what happened to a boy I babysat. He was watching Hazbin Hotel, the sister show to Helluva Boss, and told me that he got grounded and yelled at for drawing a character (nothing he drew was sexualised, or was in appropriate) that was named after a drug. Also, another note, the creator of the show is a good person, not a pedofile or a creep, just an independent animator who wants to make a show. It’s a great show and I recommend it for you or a young adult who likes musicals and cartoons. If it’s not good for you then don’t pressure your daughter into thinking she did something wrong. Support her decision and watch it with her, build a bond, and if her behaviour gets too out of hand, then lightly suggest that she watches more family friendly stuff, or if she likes indie animation, suggest something like The amazing digital circus or spooky month. Hazbin hotel, another show Vivziepop has written, which is also a great show for adults, has most of the stuff I wrote above, but it also has more depth in the characters writing (as well as helluva boss) and it shows abuse, SA, and reuniting family, and more. Both are AMAZING shows and are written beautifully, some saying its better than the recent movies Disney has put up, but that’s just millions of fans opinions. It’s good that you’re daughters telling you about the characters, and not hiding it, which I kind of find adorable, but the characters you mentioned were Blitzo, (the o is silent), who has lots of trauma involving him lighting his family circus on fire on his best friends boyfriend by accident, injuring said friend and killing her mother, ng through relationship issues with his partner who’s a prince, feeling ashamed of loving higher class demons, and Moxxie. Moxxie has a wife, isn’t really Blitzo’s friend but is an employee for him, and has daddy issues. That’s it. Watch the show. Enjoy it if you do. And don’t harass the creator.