@Miranda242 These forums are open to all, both hosts and guests. There are many threads here started by guests, just as you have done. And as Airbnb is a symbiotic relationship between hosts and guests, I think it's quite useful for hosts to be able to see things from a guest's point of view and vice versa.
I believe you can create any user name you like. There are certainly guests who are using names which aren't their real names. Of course, if your official documentation is in a certain name, there's nothing you can do about submitting that to Airbnb for your verification. But hosts aren't privy to that info- we don't see the ID you submitted to Airbnb. We don't see your phone number until after a booking is confirmed, and we never see your email address unless you provide it to us.
As far as your safety and being open with hosts about your gender identification, hosts who are discriminatory are booted off Airbnb if their behavior is reported. If I were in a demographic that often experienced discrimination, I would be fine with letting a host whose place I was interested in renting know about myself by sending an Inquiry message before committing to a booking, because that would ensure my safety. It should be pretty easy to tell from the response you would get from a host as to whether you would feel comfortable dealing with them. If they should respond that they really don't feel okay with that, or some excuse as to why they can't host you that's pretty transparently a cover-up, you should report them to Airbnb.
There's plenty of reasons that a guest wants to get a sense of the host before booking, that don't necessarily have anything to do with discrimination, but do have to do with safety or feeling comfortable with the host. My listing is a 20 minute walk into town, and as I only host 1 guest at a time, I have had several inquiries from single female guests, asking if the walk is safe. Of course I can't guarrantee anyone's safety, but I let them know that neither I, nor any of my guests has had a problem with that, but that they should exercise the same precautions they would in any unfamiliar area.
Sometimes guests jump to the conclusion that they are being discriminated against when their booking being declined, has nothing to do with that. I remember a post from a guest who claimed her booking request had been declined because she was black, but she was unaware that guest photos are not visible to hosts until affter a booking is confirmed. When looking at her profile, it was pretty obvious why a host might have declined her- she was brand new to Airbnb and had no reviews (some hosts who've had bad luck with new, clueless guests won't accept guests with no reviews), she hadn't bothered to write up any little bio on her profile, to give hosts a sense of the guest, and she had no verified ID, only a phone number. So many hosts might consider her not worth the risk, regardless of the color of her skin or anything else.
If you were to send me an Inquiry message saying, "Hi Sarah, I found your listing and it seems like just what I'm looking for. I haven't been able to figure out how to change the name on my profile here, but I want to let you know that I'm trans and wish to be addressed as Michael, rather than the birth name on my official ID. Hope to hear from you soon.", you would get a reply like, "Hi Michael, Thank you for your inquiry and I'd be happy to host you. A guest's gender orientation is immaterial to me, and none of my business, but I appreciate you letting me know how you prefer to be addressed. I will pre-approve your inquiry and hope you will see fit to go on to book with me."