I don’t know if I’m being a bad parent buying it for her or a bad parent trying to steer her away from it. Am I opening her up to being massively bullied?
I think overall the answers your received in the majority answered this for you.
I kind of feel like your recent post was written by chatgpt which I know some people do as it helps them polish up what they arr trying to say.
If your daughter has a full and bustling life outwith the home with 2-3 clubs and she has very limited access to tech. then I'd just be shutting her down with a "No" as pp said. If she presses you say that's not appropriate.
The only way kids get this info is from the internet. If she is getting this info via a friend who has unrestricted access... I'd have a frank discussion that "this is an internet hobby and we dont think its healthy". It might allow you touch upon the topics of mental health.
I've had an issue before with a very odd kid (with very weird parents) trying to befriend my child and I taught my child skills like how to deflect the conversation when a weird topic arises "have your read/watched xyz", to then walk away when they persist talking about it "oh there's X Im going to say hello" - these are useful life skills to begin practicing that will serve them well through teenage years and into adulthood. Deflect and walk away.
Your on mumsnet and Im sure you know not every commeny will be 100% what youre looking for. But I'd say the majority of responses were of a similar viewpoint.
That this is weird, to put a stop to it and to ensure your child lives a varied life offline.
The worst thing you can do is now join some "my child thinks theyre a cat" parenting facebook group which will be an echo chamber of like minded parents who fully support you letting your daughter think she is an actual cat called Luna.. Echo chambers are not where you want to move onto because youre not happy with the response here.
I wonder if you have a varied life?, you say your support network is small. Equally for you-you deserve to be in some sort of fitness class, womens group, craft group so you are a bit more supported in general.
So my overall advice is hard No on the cat stuff, shut it down and move on. Teach deflect and walk away strategies. Dpuble check she has no way of accessing weird info via devices. Ensure daughter is part of 2-3 varied clubs including a girls team sport which is well studied as having positive outcomes for girls. And finally look to expand your own support network, for your own wellbeing. Thats all my own opinion of course. Good luck 💐